Monday, 22 May 2017

Lazy journalism

This week marks the first anniversary of this blog. This is an important milestone for most blogs; and I have averaged more than one substantial post per week during that time, as I approach 60 posts. By way of celebration, this post is a bit different to most of the others.

This blog usually deals with wine data in the form of numbers, but there are other forms of data that could be used instead. One of these is industry information, as presented by the media. Sometimes, this is more opinion than properly checked information.

Consider this example from The Fabulous Ladies' Wine Society:
Cumulus Wines is a true child of the 80’s. We reckon the owners must have been listening to UB40's Red, Red Wine on repeat on their walkman when they planted out over 500 hectares of vineyard in the barely known Orange region nearly 30 years ago and built a 10,000 tonne winery with storage capacity for 8 million litres of wine. But obviously they were on to something as it has definitely paid off!
Almost everything written there is nonsense, as also is much of what is said about the same winery at Just Wines.

Cumulus Estate Wines is itself very coy about the company's history, with its description giving the impression of one continuous flow of time. However, this is far from the truth, as indicated by media reports at the time of the various events, such as those from the Newcastle Herald, Chris Shanahan (of the Canberra Times), the Pierpont column (of the Australian Financial Review), the Wine Spectator and Wine Genius. The story is long and convoluted, so here goes.

The company's main vineyard area is south of a small town called Molong, which lies just inside the Orange viticultural area of eastern Australia (the vineyard actually straddles the region's border). The vineyard, called Little Boomey, was established by Peter Poolman in 1995, increasing in size to 508 hectares over the next three years. Capital for the development was raised from hundreds of small investors, with the intention that ownership would revert to Poolman’s company after the investors had leased the vines for 15 years. What was then called Southcorp Wines (Australia's biggest wine company) bought and vinified the majority of Little Boomey’s grape harvests.

The Central Highlands Wine Grape Project, as it was officially called, was actually a tax-driven investment scheme with several vineyard areas. It was merged into a new investment company called Cabonne Limited in 1998, which was publicly listed on the Australian Stock Exchange. In 2001, Cabonne took over Reynolds Wine Company (owned by Jon and Jane Reynolds), and changed its name to Reynolds Wines Limited in 2002. It set up its wine making at Cudal, south of Molong, where a high-tech 10,000-tonne capacity winery had been built.

Reynolds Wines soon went bankrupt, slipping into voluntary administration in August 2003. The problem seems to have been what is euphemistically called an "awkward corporate structure", rather than problems with either the winery or the wine business. The company owed AU$18 million in taxes — presumably, the Australian Tax Office wasn't convinced that the original vineyard schemes were truly tax-deductible (a decision that they also applied to other vineyard small-investor schemes).

At the time, the subscribers to the original tax-minimization schemes apparently still owned, as license holders, the grapevines on Reynolds' three properties (reverting to Reynolds between 2012 and 2018), and also had rights to the wine made from those vines. The wine was concurrently being sold through a joint venture with the Trinchero group, from the Napa Valley in California (currently the fourth biggest winery in the USA, by case sales). As a result, Trinchero Family Estates acquired the Reynolds and Little Boomey brand names early in 2004, but had no interest in buying either the winery's production facility or its 900 hectares of vineyards.

The bankruptcy receiver (appointed by the ANZ Bank) sold the Cudal winery, the adjacent 508 hectares of vineyard and other assets to Cumulus Wines Proprietary Limited for AU$30 million — much less than the AU$130 million that Cabonne is reported to have invested in developing the property. Cumulus agreed to underwrite the bank loan only, which means that none of the investors got their money back, neither the original grape leasers nor those later investing via stock-exchange shares (ie. the bank came out of this okay but no-one else did!).

The Cumulus Wine company had been set up in 2004 by an underwriter and insurer called Assetinsure Proprietary Limited (50% owned by investment bank Babcock & Brown), based in Sydney. Philip Shaw (former Southcorp head of production) was appointed as the winemaker to develop the new wine company, focusing on cool-climate grapes from Orange and elsewhere in the Central Ranges viticultural area. The Little Boomey vineyard was re-named Rolling. In 2005, Keith Lambert (another former Southcorp chief executive) acquired a 51% stake in the company.

A worldwide distribution network was established. However, this proved to be overly ambitious, in spite of grants from the Export Market Development Grants Scheme, from the Australian government. So, in 2007 the Berardo wine family, of Portugal, bought the 51% share-holding. The Berardo Group has extensive wine investments in Portugal, via the Bacalhôa Vinhos de Portugal group, a 33% stake in Sogrape (Portugal’s largest wine company), 25% of Henriques & Henriques Lda (of Madeira), and joint ownership of Quinta do Carmo (with Eric de Rothschild, of Château Lafite), as well as owning 50% of Colio Estate Wines (one of Canada’s major wine producers).

This partnership between Assettinsure and the Berardo Group lasted for some; and in 2013 they launched a new wine sales and distribution company, Epoch Wine Group. [Don't worry, you are now well over half-way through the saga.]

However, in 2015 Cumulus Wines was involved in a scrip-for-scrip merger (ie. shares were exchanged instead of cash) with the trading company Wine Insights Proprietary Limited. This company owns Beelgara Estate, from the Riverina viticultural area (south-west of Orange), as well as making wine from the viticultural areas of Margaret River (Moss Brothers label), Coonawarra (Riddoch Run), Mudgee (Frog Rock), Adelaide Hills (Em’s Table), Clare Valley, McLaren Vale and Yarra Valley, among othes. Beelgara Estate was formed in 2001, when a group of shareholders bought the 70-year old Rossetto Wines company, including its winery at Beelbangera, just outside Griffith. This company had then merged with Australian Wine Supply in 2004, and the Wine Insights company was created in 2012, following further acquisitions and partnerships (including contract wine-making and bottling, and bulk wine supply).

The Cumulus merger is reported to have created a joint venture producing, per year, more than 400,000 cases of wine and with a gross revenue of AU$20 million. Winetitles Media now ranks Wine Insights as the 15th largest Australian wine company by revenue (and sales of branded wine) and 20th by wine-grape intake.

However, the venture also put the Rossetto winery, at Beelbangera, up for sale, because the merged group chose to centralize its wine production at the Cumulus winery, at Cudal. This seems to mean that the Riverina grapes are now going to be transported 350 km to be processed (at Cudal), rather than being processed locally (at Beelbangera). Much worse, the Margaret River grapes would be transported 4,000 km for processing, the Coonawarra and Adelaide Hills grapes would be trucked 1,000 km, etc. Environmentally friendly this would not be (with a large carbon footprint), although the accountants must love it.

That's it, for the moment. Nothing stays the same for long in the world of Australia's large wine companies. But the next time you read a media report about some wonderful winery, you should wonder what is the reality behind it.

Monday, 15 May 2017

Opus One, and the argument for varietal diversity

The red wines from Bordeaux contain one or more of several grape varieties: Cabernet sauvignon, Cabernet franc, Merlot, Malbec and Petit verdot. (They used also to contain Carménère, but that grape is now rare in Bordeaux.) When Robert Mondavi and Philippe de Rothschild decided to make a Bordeaux-style wine from Napa-grown grapes, they naturally used these same varieties.

This wine has been known as Opus One, with its first vintage in 1979. It was the first ultra-premium wine from the USA, the California equivalent of a Bordeaux first growth, intended as a benchmark for the wines produced from cabernet grapes in the Napa Valley. It has struggled to maintain that reputation, as it has been persistently criticized for inconsistency from vintage to vintage. Certainly, other wines have surpassed it in price and/or reputation (e.g. Ridge Monte Bello has a similar Bordeaux-style aim), although they all sell considerably fewer than the 25,000 annual cases of Opus One.

This inconsistency bears looking into. I contend that it has at least something to do with the variation in grape varieties.

The wine started out as a blend of mainly cabernet sauvignon, along with some cabernet franc and merlot. Then, malbec was added to the blend in 1994, and petit verdot was added from 1997 onwards. The proportion of these grape varieties in the wine has varied from year to year, as determined by the winemakers. The winemakers were Tim Mondavi and Lucien Sionneau from 1979–1984, and Tim Mondavi and Patrick Léon from 1985–2000, with Genevieve Janssens assisting from 1991–1997. Michael Silacci has been the chief winemaker since 2001, along with either Tom Mondavi or Philippe Dhalluin.

In this blog post I wish to look at the variation through time in the diversity of the grape varieties within the wine. A number of mathematical measurements of diversity have been developed in science, for making precisely this sort of comparison. The idea is to reduce the proportions of the various grape varieties down to a single number (for each vintage) that quantifies their diversity, from a single grape variety at one mathematical extreme to equal amounts of each grape variety at the other extreme.

The one I will use here is called the Shannon Diversity Index (see Wikipedia). This Index will be a number between 0 (for a single grape variety) and the natural logarithm of 5 (for equal amounts of each of the 5 varieties). The data for each vintage come from the Opus One web site. The variation in Shannon diversity is shown in the first graph, with the vintages plotted horizontally and the diversity plotted vertically.

Grape diversity through time for the Opus One wine

This graphs shows that there was a lot of variability between the first few vintages, while the winemakers worked out what wine style they were aiming for. Furthermore, from the early 1990s onwards the diversity has steadily increased. This has been partly the result of using five grape varieties, as opposed to the original three, but it is mainly a result of using greater proportions of the minor varieties. In the early years, there were vintages composed of >95% cabernet sauvignon, but over the past 10 years it has been closer to 80%. For the rest of the grapes, it has been c.7% merlot, c.6% cabernet franc, c.6% petit verdot, and c.1% malbec.

Having established that the winemakers have been moving towards a greater diversity of grape varieties in Opus One, we can now ask whether this has improved the wine quality in the eyes of the drinkers. There have, of course, been a number of retrospective tastings of the vintages of Opus One, which is getting closer to its 40th vintage. It therefore seems worthwhile to see whether the quality scores given to these wines are associated in any way with the particular mixture of grape varieties that have been included in the wine over the years.

The most complete vertical tasting that I have been able to find is that of Antonio Galloni, from 2013, which included all of the vintages from 1979–2010. Sadly, the best vintage of all has been suggested to be the 2013, which misses out. In the next graph I have plotted Galloni's quality scores (vertically) against the Shannon diversity (horizontally), with each point representing a single vintage.

Wine quality and grape diversity for the Opus One wine

The graph shows a general increase in quality score with increasing diversity, with four exceptions (as labeled in in the graph). Excluding these four vintages for the moment, a correlation analysis shows that 42% of the variation in the wine quality score is associated with the grape diversity score. That is, increasing the diversity of the grape varieties in the wine has generally improved the quality, which is presumably what the winemakers have intended.

The four exceptions are instructive. The 1980, 1984 and 1987 vintages consisted almost entirely of cabernet sauvignon (>95%), and this has obviously been a very erratic strategy in terms of wine quality (sometimes it worked and sometimes it didn't). Furthermore, the 1980 and 1984 vintages consisted solely of cabernet sauvignon and cabernet franc, with no merlot at all. On the other hand, the 2006 vintage had the highest proportion of merlot yet, at 12%, which is double the usual amount. This created a high diversity value but obviously not a high quality score from Galloni. The winemakers again tried such a high proportion of merlot for the 2011 vintage (11%), and Galloni's preliminary score for the resulting wine (not yet released) indicated that he didn't think it had worked then, either.

This pattern could, of course be unique to Antonio Galloni — I have repeatedly pointed out that wine critics rarely agree much with each other about wine quality (see How large is between-critic variation in quality scores?). However few of the other professional commentators have conducted extensive vertical tastings of Opus One. So, by way of comparison, let's look at the opinions of a group of non-professionals.

In 2002, Bob Henry, a wine marketer from California, conducted a group tasting of the first 20 vintages of Opus One (1979–1998). Each of the 23 tasters was asked to rank their top three wines, with 3 points being assigned to the top wine, 2 points to the second wine, and 1 point to the third wine. These scores were then summed across the tasters, in order to rank the quality of the vintages. These results are compared to those of Galloni in the next graph, with each point representing one of the 20 wines.

Quality scores for vertical tastings of the Opus One wine

As you can see, only nine of the wines scored any points (ie. was a top-3 wine for any of the tasters). Most of these wines were also high-scoring wines for Galloni, and so we can treat this as a general confirmation of his scores. However, note that the 1980 vintage, which had a low grape-diversity score but still received 95 points from Galloni anyway, was not a high-scoring wine for the tasting group. This means that only the 1987 wine scored points but had a low grape-variety diversity. Indeed, the 1991 vintage was the only high-scoring wine before the introduction of malbec and petit verdot to the mix.


In biology (including agriculture), diversity is considered to be a Good Thing. Here, the Opus One wine seems to support this idea, as increasing diversity of grape varieties is associated with higher quality wines. Furthermore, the winemakers have been steadily increasing this diversity with each succeeding vintage. This is a strong argument for varietal diversity in wines. If nothing else, this helps explain the wine's reputation for inconsistency — poor vintages have generally arisen from reliance on too few grape varieties.

Monday, 8 May 2017

The Wine Spectator prefers modern wine styles

In some recent posts I have compared the wine-quality scores provided by different commentators. While doing the data analyses, I noticed that the scores from the Wine Spectator magazine had a particular pattern that the other scores did not — there was a time trend to the scores.

For example, in the post on Poor correlation among critics' quality scores, I compared the quality scores from five commentators over 60 vintages of the Penfolds Grange wine. There was no time trend in the scores for four of the commentators, but the Wine Spectator showed a very clear upwards trend in the scores through the vintages, as shown in the first graph. [Note: most of these wine scores were not given at the time of release, but are based on subsequent retrospective tastings.]

Wine Spectator quality scores for Penfolds Grange

For comparison, the time correlation value for the other commentators ranges from 7% to 18%, versus 58% for the Spectator. So, for the Wine Spectator more than a half of the variation in the scores is associated with time, which is not true for the other commentators.

The line in the above graph is a running average (of 9 vintages), showing that the scores rise until the early 1990s, and then remain somewhat steady after that. Indeed, it was in 1995 that the Wine Spectator named the 1990 Penfolds Grange as its wine of the year.

This intrigued me, so I looked for other long-term data from the Wine Spectator. I looked for a broad range of wine types (different styles from different regions), since the Spectator has a range of different reviewers, and I wanted to include as many of these as possible. For each wine, I wanted at least 10 scores from the period 1975-2014 (40 vintages), with some of the scores before and some after the 2000 vintage. What I came up with is shown in the table, with the time correlation indicated for each wine.

Schloss Vollrads Riesling Spätlese, Rhine
Ruffino Riserva Ducale, Chianti
Schloss Johannisberg Riesling Spätlese, Rhine
E. Guigal Château d'Ampuis, Rhône
Fontanafredda Serralunga d'Alba, Barolo
J.J. Prüm Wehlener Sonnenuhr Riesling Auslese, Mosel
Viña Tondonia Reserva, Rioja
Penfolds Grange Bin 95, Barossa
Louis Latour Corton Grand Cru, Bourgogne
Viña Tondonia Gran Reserva, Rioja
Château Latour, Bordeaux
Moet & Chandon Brut, Champagne
Château Lafite-Rothschild, Bordeaux
Henschke Hill of Grace, Barossa
Château Climens, Bordeaux
Robert Mondavi Winery Cabernet Sauvignon, Napa
Château Mouton-Rothschild, Bordeaux
Château Margaux, Bordeaux
Stag's Leap Wine Cellars Cabernet Sauvignon, Napa
Joseph Drouhin Charmes-Chambertin Grand Cru, Bourgogne

As you can see, the majority of the correlations are high — in this context, any correlation greater than about 20% is unusually high. As an illustration of what a 25% correlation looks like, in the next graph I have included the data for two of the Bordeaux chateaux for the period since 1980.

Wine Spectator quality scores for Chateaux Latour and Lafite

It turns out that I am not the first person to have noticed this pattern. In a blog post entitled Fun with wine numbers, Tom Wark looked at the Wine Spectator's point scores for several hundred California chardonnays over 18 years. He summarized the data in terms of the percentage of wines with particular scores; and I have graphed his results in the next figure.

Wine Spectator quality scores for California chardonnays

The decrease in the percentage of wines with scores <80 is the result of an editorial decision to stop publishing such scores (there are plenty of wines with high scores to write about). However, the increase in the percentage of wines with scores >90 is precisely what I have shown above for individual wines.

Why has this happened?

This leads inevitably to a consideration of what is causing this time pattern. Tom Wark commented: "I honestly don't know what to make of this. It looks like point inflation taking place ... On the other hand, it just may be that CA Chardonnays got a heck of a lot better."

The Wine Spectator itself agrees with the second option. Writing in that magazine, James Laube (Wine rating inflation) noted: "It's indisputable that wines are better now than a generation ago. Vineyard management, winery technology, winemaker skill — all have progressed. And as wines have improved, ratings as reflected by scores have risen."

However, not everyone else agrees with this idea. If we take the Henschke Hill of Grace wine listed above, for which the Spectator time correlation is 26%, the time correlations for the same period from some other commentators are: Jancis Robinson 0%, Jeremy Oliver 4%, James Suckling 5%, Huon Hooke 25%, and Robert Parker 26%. So, two of the critics agree with the Spectator about increasing quality, and three don't.

It is inevitable that Parker's wine scores went up, of course. Lots of winemakers started making "Parker wines" precisely for the purpose of getting high "Parker scores", and so it is inevitable that Parker would prefer later wines to the earlier ones — they were made especially for him. In this sense, Parker is simply the victim of his own excess — his strong wine bias has helped create a wine world that suits him well, but not necessarily anyone else, including other wine commentators. The wines styles do, however, seem to suit the palates at the Wine Spectator.

This is not really score inflation, but is instead simply another example of confirming the consequent. It is a feedback loop, in which high scores encourage wine makers to produce wine styles that will generate more high scores.

To examine the idea that the Wine Spectator's scores reflect score inflation, instead of better wines, we would need data that are independent of Robert Parker, which we do not have. However, it is worth noting that the Spectator's higher scores for recent wines occur even in vertical tastings, where all of the vintages are tasted at the same time. So, the high scores do not represent a slow creep upwards through time, but are instead a clear preference for modern wines compared to older styles.

Modern wine styles are associated with the change to riper vintages since 1990 (often attributed to global warming; see Fifty years of Bordeaux vintages), which produce "bigger" wines with higher alcohol contents. If you want to read about such things, then Dan Berger has a long series of posts in his USA-syndicated wine column (thanks to Bob Henry for pointing these out to me):
Big wines
Bored with big wines?
Bigger is better?
Bigger: Is it better?
'Big' wines
Is bigger better?
High alcohol
A troubling trend?
Another look at high alcohol content
How much alcohol should wine have?
Blind tasting and alcohol
High alcohol and diminishing wine styles

Monday, 1 May 2017

Do sales by US wine companies fit the proverbial "power law"?

The short answer is: almost.

The Power Law is used to describe phenomena where large events are rare but small ones are quite common. For example, there are few billionaires while most people make only a modest income; there are few large cities but many small towns; there are few very frequent words (such as "and", "the") but many rare words.

Mathematically, Power Laws are of interest because of what is known as "scale invariance", as well as the fact that there is no well-defined average value. You can read about this in Wikipedia.

For the rest of us, Power Laws are of interest because of their practical consequences. For example, the 80:20 Rule (or Pareto Principle) is one example of a Power Law, which says that for many events, roughly 80% of the effects come from 20% of the causes. You can also read about this in Wikipedia. For a discussion of this idea, see What is the 80/20 rule and why it will change your life. [Sometimes, it is also 90/10; for example, it is usually estimated that 90% of wine consumption in the USA is by 10% of the people.]

Power Laws are considered to be universal, and so there is no reason why they should not exist in the wine industry. One of the more obvious places that we might expect to find them is in the size of wine companies. Size might be measured by amount of wine produced or by monetary income, for example. Either way, there will be a few very big companies and lots of little ones.

So, let's look at a specific example. In its February 2017 issue (p.48), Wine Business Monthly compiled its fourteenth annual ranking of the top 30 U.S. wineries by case sales (in 2016). You can see a copy of the list in Big Wine takes over.

Wine Business Monthly notes:
Though there are now 9,091 wineries in the U.S., the WBM 30 companies represent more than 90 percent of domestic wine sold by volume. The three top wine companies by themselves represent more than half of all case sales.
This sounds like a classic case of a Power Law; and so it is worth checking this possibility.

One special case of the Power Law is known as Zipf's Law, which refers to the "size" of each event relative to it's rank order of size. This is what we are looking at here. For each wine company, the "size" is the number of cases of wine sold during 2016, and the WBM 30 companies are listed in rank order of their sizes (largest to smallest).

The standard way to evaluate the Zipf pattern is to plot the data with both axes of the graph converted to logarithms. Under these circumstances, the data should form a straight line. Here is the graph of the WBM 30 data. The three largest wineries are labeled.

A Power Law fitted to the sales by US wine companies

As you can see, almost all of the data lie roughly along a straight line, and thus do indeed fit a Power Law. That is as expected; and the Power Law is thus not proverbial in this case.

However, there is one exception — the largest company, E&J Gallo Winery, did not produce enough wine to fit into the same pattern as the other 29 wineries. Indeed, to fit the Power Law, the top-ranked company would need to have sold about 260 million cases during 2016, which is c. 3.5 times as much wine as E&J Gallo actually sold.

This is an interesting finding. The Power Law suggests that the biggest US winery (and thus the biggest wine company in the world) should dominate the US industry to a greater extent than the Gallo winery currently does. That is, having one-quarter of the US wine market is not enough! The current degree of industry dominance has been held by Gallo for at least the past quarter-century, but it seems unlikely that it has ever dominated sufficiently to fit the Power Law. Apparently, it is rather hard to dominate US wine sales in the way predicted by a simple Power Law model.

This "under-performance" by Gallo may be a good thing for the consumer, of course, since Diversity is usually a better thing than is a Power Law — the Power Law actually represents a rather extreme situation.

For comparison, the biggest-selling imported wine in the USA is Yellow Tail (from Casella Wines, in Australia), with more than 8 million cases shipped to the US per year. This would place it at no. 9 in the WBM 30 list. This will be the subject of a separate blog post.

Monday, 24 April 2017

Be wary of "Second Chance Offers" on eBay

Wine cannot be advertised for sale on the English-language eBay sites without a liquor license (e.g. in the U.S.A., U.K., Australia, Canada, Ireland). However, it can be sold privately on many of the mainland European sites (eg. Austria, Belgium, France, Germany, Italy, Netherlands, Spain), except to minors. The wine can then easily be sent anywhere within the European Union. Indeed, many European wine shops use eBay as one of their online portals.

This is generally a Useful Thing for customers, because older vintage wines are widely available, usually much cheaper than in wine shops or at other auctions. However, the buyer must beware. In eBay terms, for older wines you are formally buying the bottle, not its contents, since there is no independent evaluation of the condition of the wine, as occurs for other auctions (and for which the buyer is charged a substantial premium).

I have purchased some very nice wines from 1945-2000 this way, although I have also had a few rather mediocre ones.

I have not yet been ripped off. Indeed, eBay prides itself on dealing with shonky activities by its members, although these activities still exist, and will presumably continue to do so. Last year, I encountered the following example, which I explain here for your education, because it involves a general issue with eBay.

A Milan-based seller became active selling old vintages of Barolo wine. This in itself is not unusual, but what attracted my attention was that the seller was offering free shipping, apparently worldwide. That is very unusual, because international shipping costs from Italy (even within the European Union) are often more expensive than the wine itself. How could the seller afford this? Buyer beware!

So, I decided to keep a curious eye on several of the wines. When I did so, an unusual bidding pattern appeared.

I have attached at the bottom of this post images of the final bidding results for all seven of the wines that I followed. Many more wines were offered by the seller, but I did not check their results. You will note that in all seven cases a previously unknown bidder (ie. one who had never bought anything on eBay before) put in a late bid. In six of the seven cases this newbie bidder won the auction.

This is a quite unbelievable coincidence, and I do not for one moment believe it. I occasionally see newbies bidding high prices on wine, but not seven different newbies bidding on all of the wines that I happen to be watching. If you are prepared to accept this, then I have this bridge in Brooklyn that I would like to sell you ...

Indeed, this looks exactly like shill bidding — defined as "bids on an item with the intent to artificially increase its price or desirability." Normally, the shill bidder does not win the item, but merely forces the other bidders into bidding unnecessarily high, preferably by forcing them to their maximum possible bid. This happened for one of the seven auctions shown below (the fourth one), in which an inexperienced bidder paid €151 for a wine that no-one else thought was worth more than €100. So, the shill bidder managed to extract an extra 50% of profit from the auction. This also happened for the third auction.

The other five auctions require a somewhat different explanation for their profitability.

Unfortunately, eBay has a mechanism that allows shill bidders to ostensibly "win" the item while still achieving their purpose of forcing another buyer to pay more for the item than they needed to. This is called a Second Chance Offer. After the auction, the highest losing bidder is contacted by the seller and told that they have another chance to buy the item, by paying their maximum bid amount.

So, the purpose of the shill bidding in this case is to reveal, to the seller, the buyer's maximum bid. Normally in an auction, the maximum bid for the highest bidder is not revealed to the seller, only the fact that they bid higher than everyone else. Of course, all of the losers' maximum bids are revealed.

Let's take one example from below, the sixth one. The highest bid is the shill bid (from bidder t***t), which was more than €114 — we do not know the actual bid, but one of the other examples (the fourth one) suggests that it was most likely €150. The second highest bid was €112.98 (from genuine bidder 7***8), and the third highest was €79 (from genuine bidder o***2). This means that, without the shill bid, the item would have sold for €79.50 to bidder 7***8. Instead, a Second Chance Offer is sent to 7***8 for sale of the item at €112.98, with a handsome extra profit of €33 to the seller (in collaboration with the shill bidder, who may or may not actually be a separate person).

Note that this approach to shill bidding does also deal with snipe bidders (ie. those who bid during the last few seconds of the auction — there are some examples below). Snipe bidding is sometimes considered to be immune to the actions of shill bidding (eg. How to snipe a winning bid), but it is not immune to the Second Chance Offer problem on eBay.

Caveat emptor. Be very wary of eBay's Second Chance Offers. If you want to play safe, ignore them.

Fontanafredda 1990

Marchesi di Barolo 1990

Pira e Figli Riserva 1990

Marengo Marenda Cerequio 1989

Michele Chiarlo 1988

Franco Fiorina 1955

Conterno Bricco Bussi Vigna Cicala 1990

Note: This post is modified from a post on my other blog: The Genealogical World of Phylogenetic Networks.

Monday, 17 April 2017

Was the Judgment of Paris repeatable?

A few months ago I wrote a blog post for the Academic Wino, discussing the 1976 wine tasting that has become known as the Judgment of Paris, organized by Steven Spurrier and Patricia Gallagher. Here, wines from France were tasted along with some wines from California, and the latter acquitted themselves very well in the opinions of the tasters.

Given the outcome of this tasting, it is possibly the third most important event in the social and economic history of wine in the USA, after the imposition and then repeal of Prohibition. It was certainly made much of by the media during the Bicentennial; and this has been repeated every 10 years since. World wine was henceforth taken seriously, not just the European wines.

However, one of the things that struck me most strongly about this tasting was just how variable the results were amongst the tasters — hardly any of the tasters agreed closely with each other about the quality scoring of the wines, and especially about which wines were the best among the 10 reds (bordeaux grapes) and the 10 whites (chardonnays).

This immediately calls the repeatability of the results into question. After all, only one bottle of each wine was tasted, on one occasion, by one group of people. What would happen under other circumstances?

This is particularly important to me as a scientist, because it is the ability to independently repeat an experimental result that is considered to be the only really good evidence in science. For example, if no-one else can replicate my experiments for themselves, then my results will not be widely accepted in the scientific community.

So, given that it is common knowledge that the results of wine tastings are often barely repeatable, why was the Judgment of Paris tasting not widely repeated by other people at other places? The results were widely reported, but apparently only Frank J. Prial, writing in the New York Times (June 16 1976, p. 39), warned against taking the unreplicated wine-tasting results too seriously: "One would be foolish to take Mr Spurrier's little tasting as definitive." And yet, this is what the media very much did.

A first attempt at replication

However, Robert Lawrence Balzer did partly replicate the tasting, later in the same year. Balzer was among the earliest of the wine journalists in the USA, specializing in California wines. He was the wine columnist for the Los Angeles Times, and he also wrote his own newsletter, Robert Lawrence Balzer’s Private Guide to Food and Wine. More importantly, he had previously (in 1973) organized an important tasting of French and US wines, in New York (see Wikipedia).

So, if anyone was going to try replicating the Judgment of Paris, and publish the results, it was likely to be Balzer. The resulting tasting was discussed on pages 77-84 of Volume 6 Number 8 of his newsletter. [Thanks to Christine Graham for kindly sending me a copy of this article.]

Unfortunately, Balzer explicitly stated that his tasting was inspired by the Judgment "without any attempt at exact duplication". This is a pity, because an attempt at exact duplication is what we require. So, Balzer had only 9 of the 20 wines duplicated exactly, while some of the others differed either as to vintage or producer, and some were completely different.

For the red wines, 6 wines were identical to the Paris tasting (4 from the US, 2 French), 2 had different vintages (both French), and 2 of the Paris wines were not tasted (both US). For the white wines, 3 were identical (all US), 4 had different vintages (2 US, 2 French), 1 differed as to producer (French), 1 differed as to both vintage and producer (French), and 1 was not re-tasted (US). For the French wines, it was at that time recognized that there could be big differences between wines from different producers even when harvesting grapes from the same vineyard, and also between vintages from the same producers; and so, these differences prevent those wines from being treated as repeats of the Paris tasting.

The results for the 9 repeated wines, averaged across the 9 tasters' scores, are shown in the first graph, with the red wines in blue and the whites in green. If the scores of the two tastings were identical, then the points should lie along the pink line.

The results of the Balzer tasting

The scores for the American tasting are considerably higher than those of the Paris tasting. The Americans presumably were using the UC Davis 20-point scoring system, which the French tasters were definitely not. The Davis system does not use very much of the 20-point range, as it reserves a large part of the range for faulty wines, which was an important part of its development as a teaching tool (see Steve De Long's comparison of wine scoring systems). Even today, French tasters still often use much more of the 20-point range than do Americans (eg. La Revue du Vin de France).

In spite of this, the scores from the two tastings are correlated — indeed, 67% of the variation in the Balzer scores is directly related to the Paris scores. This is quite a good degree of repeatability. However, it is not the complete picture.

First, note that the rank order of the white wines is not the same in the two tastings — the Chateau Montelena 1973 Chardonnay was ranked first in the Paris tasting, while the Chalone Vineyard 1974 Chardonnay was ranked first in the Balzer tasting. Second, the red wines form two score groups in the Paris tasting, whereas they do not in the later tasting — indeed, the Château Montrose 1970 and the Mayacamas Vineyards 1971 Cabernet had the same average score in the Balzer tasting, whereas they had very different scores in Paris.

Perhaps more importantly, however, the erratic nature of the wine preferences among tasters was repeated in the American tasting. For example, among the red wines, only one person actually chose the Stag's Leap Wine Cellars 1973 Cabernet as their top-scoring wine, in spite of the wine getting the highest average score — and even that person scored it joint top with Château Léoville-Las-Cases 1970. In fact, the 9 tasters chose 7 different wines as their top-rank! The whites were no different, with only one person recorded as picking the Montelena as their (joint) top wine.

First, but only in one out of three tastings.

So, the things that were repeatable at the repeated tasting were a lot of the "wrong" things. The unreliability of wine tastings was strongly in evidence, and the preference rankings varied (particularly the "winner" among the whites).

A second replication

The only other published tasting that was a serious attempt to evaluate the results of the Judgment tasting occurred nearly 2 years afterwards, in January 1978, at the Vintners Club. This club was formed in San Francisco in 1971, to organize weekly wine tastings (usually 12 wines). Remarkably, the club is still extant (having had only four presidents), although tastings are now monthly, instead of weekly. The early tastings are reported in the book Vintners Club: Fourteen Years of Wine Tastings 1973-1987 (edited by Mary-Ellen McNeil-Draper. 1988).

For the Judgment of Paris replication, 98-99 people tasted the wines over two evenings (white then red), "with Steven Spurrier himself in charge". The tasting allegedly "duplicated [the Paris] tasting to the last bottle", but in fact the vintage listed for the Bâtard-Montrachet Ramonet-Prudhon differs from the Paris event, leaving 19 duplicated wines. The Vintners Club has "always kept to the Davis point system" for its tastings; and so the scores were higher than for the Paris tasting, as discussed above.

The next graph shows the results for the 19 repeated wines, averaged across the 88 (red) and 55 (white) people who provided scores; once again, the red wines are in blue and the whites in green.

The results of the Vintners tasting

As before, variability of the results is the name of the game. Indeed, every red wine was placed first by at least one of the tasters, as well as being placed last by at least one of the tasters; and every white wine was placed first at least once, except for the David Bruce Winery 1973 Chardonnay, and every white was placed last, except for the Chalone Vineyard 1974 Chardonnay.

The Vintners book claims that "the results were very similar to the preceding tasting in Paris", but in fact the scores from the two tastings are not well correlated at all. For the white wines, only 35% of the variation in the Vintners scores is directly related to the Paris scores; and for the red wines it is a measly 10%. For tastings of the same wines under reasonably similar circumstances, these are very low values, and they indicate very poor repeatability.

For the red wines, the Stag's Leap Wine Cellars 1973 Cabernet was placed 1st, as it had been in the previous two tastings. However, the Heitz Wine Cellars Martha’s Vineyard 1970 Cabernet was placed 2nd, having been placed 9th in Paris. For the white wines, the Chalone Vineyard 1974 Chardonnay was placed 1st, as it had been in the Balzer tastings (3rd in Paris), with the Chateau Montelena 1973 Chardonnay placed 2nd (1st in Paris).

With one exception, the Balzer and Vintners tastings are reasonably well correlated (64% of the variation in common), although the Balzer group's scores were (on average) 1 point higher per wine than for the Vintners group. The exception is the Heitz Wine Cellars Martha’s Vineyard 1970 Cabernet, which the Balzer group scored as 14.6 and the Vintners group scored as 16.9. The Spurrier group's result is more in accord with the Balzer group, for this wine.


Neither of these two tastings inspires much confidence in the replicability of wine tastings, let alone the repeatability of the Judgment of Paris in particular. Even to this day, I still read of people expressing the opinion that the difference between Californian and French wines is "obvious". Well, it wasn't obvious to the people at any of these three tastings.

As Mike Steinberger noted in Slate (Nov. 7 2007, In blindness Veritas?): "there is a tendency to overlook the fact that wines and palates are fickle, and to read more into the results than is justified. This was certainly true of history's most famous blind tasting, the 1976 Judgment of Paris".

You will, however, have noted, I am sure, that all three tastings produced a California wine as the "top" for both the reds and whites! There is simply some disagreement about which one it is.

There seems to be little here that supports the media hoopla that ensued in 1976, at least in terms of California versus France "winners". It was the California wine industry that was the big winner, not the individual wines.

Monday, 10 April 2017

Napa versus Bordeaux red-wine prices

In a recent article on Wine-Searcher, Blake Gray addressed the question: Does Napa have too much Cab? The accountant answer is: "not if you can sell it", which is a very short-term point of view. Somebody with a longer perspective would be more interested in whether the domination of the Napa Valley vineyards by cabernet sauvignon wines is sustainable, because sustainability is related to biodiversity, not to monocultures.

Blake looks at the issue by making some comparisons between the Napa area of California and the Bordeaux region of France, whch also relies on cabernet as a principal grape. Let's look at some of the points made in the article.

First, cabernet sauvignon comprises nearly half of the vineyard area in Napa, which is certainly not a monoculture, but it is also quite a domination. How does this domination compare to Bordeaux? Actually, the comparison need to be among all of the common grape varieties, because Bordeaux has more merlot than cabernet.

A number of mathematical measurements of what is called "diversity" have been developed in science, for making precisely this sort of comparison. The idea is to reduce the various grape-variety areas down to a single number that quantifies their diversity, from a monoculture of one grape variety at one extreme to equal amounts of each grape variety at the other extreme.

The one I will use here is called the Shannon Diversity Index (see Wikipedia); and I will apply it to the vineyard area of each of the seven most common grape varieties in both Napa and Bordeaux. The Index will be a number between 0 (for a monoculture) and the natural logarithm of 7 (for equal amounts of each grape variety). The data come from Blake Gray's article for Napa, and from the Wine Cellar Insider for Bordeaux.

It turns out that Napa (1.51) actually has a slightly greater diversity of grape varieties than does Bordeaux (1.28). So, we certainly cannot yet claim that there is anything unusual about the domination of Napa by cabernet sauvignon. However, there seems to be no reason why Napa won't eventually exceed Bodeaux, if the current trends continue.

[Aside: Blake Gray makes the erroneous claim that Europe has grapes that are "disallowed" in certain regions. No grapes are disallowed anywhere in Europe; and any type of wine can be made in any region. What is disallowed is the name that can be used for those wines — names must match the definition of those names. In Bordeaux, in addition to its top seven grape types, which are Merlot, Cabernet Sauvignon, Cabernet Franc, Semillon, Sauvignon Blanc, Malbec and Muscadelle, there are also notable areas of: Petit Verdot, Carménère, Sauvignon Gris, Colombard, Folle Blanche and Ugni Blanc.]

Moving on, Blake Gray points out that Napa winemakers charge the consumer more money for their cabernet wines than do the winemakers of Bordeaux. He quantifies this claim by looking at the most popular wine searches on Wine-Searcher, for the cabernet blends of both Napa and Bordeaux. Search popularity is a convenient way to compare the wine regions, especially as it turns out in practice that the most expensive wines are the most popular searches.

Blake does not show us a picture of the dollar comparison, but we can generate one of our own. As of 18 March 2017, c. 450 of the most popular 500 searches on Wine-Searcher for both Napa and Bordeaux involve wines dominated by one or more of the principal Bordeaux red-wine grapes (cabernet sauvignon, merlot, cabernet franc, malbec). Now, that's what I call domination!

These two lots of 450 wines are the ones that I have compared in the first graph. The two lines show a running average of the Wine-Searcher average bottle price (vertically) against the Wine-Searcher search popularity (horizontally). [The running average is based on nine-year blocks.]

Napa and Bordeaux wine prices relative to search popularity

For the first 30 most-popular searches, the Bordeaux wines are more expensive than are the Napa wines, but after that the Napa wines are consistently 2–3 times more expensive than the Bordeaux wines. The exception is for the Le Pin wine from Pomerol, which is ranked 45th in search popularity but is the second most expensive Bordeaux wine. Furthermore, some rather expensive Napa wines have low search popularity, so that the Napa line on the graph goes up and down like a yo-yo.

Conclusion: a Napa cabernet will cost most of us a lot more money than will a Bordeaux wine, unless we go for the few most expensive Bordeaux wines.

It turns out that this pattern is independent of wine quality. Wine-Searcher also provides an average quality score for each wine, averaged across a number of wine critics. So, we can compare the Quality:Price Ratio for the two regions, as well.

I have done this in the second graph. Each point represents one of the 450 wines from each region, plotted with the average bottle price (vertically) and the average quality score (horizontally). Note the log price scale, which deals with the ridiculous prices of the wines from Screaming Eagle (Napa), Petrus (Pomerol) and Le Pin (Pomerol), at the top of the graph. Also, shown are the exponential price models fitted to each dataset (see the post on The relationship of wine quality to price) — this is a straight line on the graph because of the log price scale.

Napa and Bordeaux wine prices relative to quality score

The Bordeaux wines, on average, score 0.7 quality points less than do the Napa wines. However, the QPR line for Napa is consistently above the line for Bordeaux, indicating that the Bordeaux wines are generally cheaper for the same quality score. This cannot be a good thing for US wine drinkers, but is much better for the wine drinkers of France (where most of the Bordeaux wines are consumed).

Note that there is only one isolated dot below the main wines, which represents the only wine with an outstanding Quality:Price Ratio, relative to the other wines. There are, however, plenty of points above the main group, which represent poor value for money!

In other words, neither Napa nor Bordeaux has red wines that represent particularly good value for money; and it seems unlikely that this situation will change any time soon (see At what price, To Kalon?).

This odd QPR wine, incidentally, is Chateau Tour Saint-Christophe (Saint-Emilion Grand Cru), with an average score of 91 points and an average cost of US$26 — this seems to be commonly available in the USA. The property was recently renovated by Hong Kong-based entrepreneur Peter Kwok, so the wine may not remain cheap for much longer.

Monday, 3 April 2017

How large is between-critic variation in quality scores?

I have written before about the Poor correlation among critics' quality scores (see also Can non-experts distinguish anything about wine?). This topic refers to what is technically called inter-individual variation in the scorer, which you might call "between-taster variation" — the same wine tasted by different people, even on the same occasion, does not necessarily receive the same quality score, even when it comes from the same bottle.

This results from two things: (i) variation in personal assessment of the wine (the assessment of quality is the result of each taster’s previous experiences as well as their personal conceptions); and (ii) differences in how this assessment is expressed in terms of a score.

This is an important issue for anyone who reads the opinions of wine commentators. After all, if there is more disagreement than agreement, then we might ask ourselves what it is that we are expecting to get out of reading the critics in the first place. It is for this reason that we are often advised to find a commentator whose wine tastes match our own, and read that person's reviews only.

This issue of inter-individual variation has been studied in the professional literature; and, indeed, many authors have concluded that wine criticism is a somewhat fraudulent activity, given the large personal component in the scores. I have included a list of relevant published papers at the end of this post.

What I will do in this post is taker a broader look at this topic than I did in my previous post, but still examine particular examples of scores from particular wines and wineries. All of the wines will be red, since it seems to be rather hard to find large datasets of white wines that have been evaluated by many people (the wines of Sauternes are the most obvious ones).

Bordeaux First Growth wines

I will start by looking at the "Grand vin" wines of the five First Growth wineries from the Left Bank of the Bordeaux region, in France: Château Haut-Brion, Château Lafite-Rothschild, Château Latour, Château Margaux, and Château Mouton-Rothschild. All five of these wines have vintages going back centuries, although most of the available quality scores cover only the period after 1900.

For each of the five wines, I have compiled as many publicly available scores as I can, using principally the information provided by Wine-Searcher, 90plus Wines and Cellar Tracker. For each wine, I then restricted the dataset to those post-1900 vintages with quality scores from at least two commentators; and then I pooled the five wines together. [Note: In the previous post I analyzed a single wine.] Finally, I separately converted all scores to use a 100-point scale.

For the analyses presented here, I have divided the data into two subsets: (i) 11 commentators with scores for at least 15 vintages of each of the five wines, covering the period from 1945–2014, inclusive; and (ii) 11 commentators with scores for at least 14 vintages of each of the five wines, covering the period from 1988–2014, inclusive.

There are eight commentators who appear in both datasets (Falstaff Magazin, Jeff Leve, Robert Parker, Jean-Marc Quarin, Jancis Robinson, James Suckling, Stephen Tanzer, Wine Spectator), and six who appear in one but not the other (Michel Bettane and Thierry Desseauve, Jeannie Cho Lee, Richard Jennings, John Kapon, La Revue du Vin de France, Vinum Weinmagazin). There are many well-known sources of Bordeaux wine commentary for whom I could not find sufficient data, including Wine Enthusiast, Decanter, Vinous (Antonio Galloni), Gault & Millau, Wine & Spirits Magazine, and Tim Atkin. It is worth noting that most of the Wine Spectator's scores were actually from James Suckling, along with a few from Thomas Matthews, James Molesworth and Harvey Steiman (who have all reviewed the red wines of Bordeaux for that magazine), plus some that were unattributed.

So, we can now look at how similar are the quality scores of these commentators, when pooled across these five wines. [Aside: the picture does not change much if we consider each of the five wines separately.] Let's start with the first dataset, covering the period since the 1945 vintage. All of these commentators are from the USA except for Jancis Robinson (UK), Falstaff Magazin (Austria) and Jean-Marc Quarin (France).

As before, we can quantify the relationships among the scores using correlation analysis. This analysis reveals that the following percentages are held in common between the 11 commentators pairwise. In this table, values >60% are highlighted in green, those between 50 and 60% are in blue, and those <10% are in yellow.

Table showing correlations among the quality scores of 11 wine critics

As far as wine quality is concerned, the average agreement among the commentators is less than 50% in almost all cases, and more than half of the values are in the range 10–40%, which is rather low. Certainly, the critics disagree with each other much more than they agree. The only commentators who appear to be in strong agreement with each other are Jeff Leve and Robert Parker. At the other extreme, neither Jancis Robinson nor Richard Jennings has much in common with the other commentators.

It might be more useful to look at a picture of these data, rather than a table of numbers. To do this, we can employ a network, as described in the post on Summarizing multi-dimensional wine data as graphs, Part 2: networks. This is shown in the next graph. [Technical note: the correlation scores were first converted to euclidean distances, and the NeighborNet graph was drawn using the SplitsTree program.]

Network showing similarities among the quality scores of 11 wine critics

In this graph, the lengths of the lines represent the amount of information. The interconnected lines in the centre represent the shared information, with the terminal lines ("leaves") representing the unique information. In this case the longest lines are the terminals, indicating that there is little commonality among the quality scores.

The connections among the lines represent who is agreeing with whom. For example, Parker and Leve are closely associated in the network, as expected from the results shown in the table above (their association is indicated by the short distance separating them along the lines of the network). You can see that there is also some association between Tanzer and Cho Lee, between Suckling and Kapon, and between Robinson and Jennings (and also between Robinson and Kapon). The Spectator magazine and Jean-Marc Quarin appear to have some similarity to the scores of Robert Parker; but the relationships of Falstaff magazine are unclear. It is worth noting that the scores of Suckling and the Spectator are not closely associated, in spite of the fact that most of them come from the same person (see Are the quality scores from repeat tastings correlated?).

We can now do the same two analyses for the second dataset, covering the period since the 1988 vintage. The correlation analysis reveals that the following percentages are held in common between the 11 commentators pairwise.

Table showing correlations among the quality scores of 11 wine critics

A similar pattern emerges, although the average values are slightly larger for this restricted dataset. The average agreement among the commentators is still less than 50% in most cases, and more than half of the values are in the range 10–40%. Thus, the critics disagree with each other much more than they agree. However, in this dataset there are now several pairs of critics who share more than 50% agreement. Jancis Robinson is once again involved in the values that are less than 10%

The network picture of the same data is shown in the next graph. Several of the previous associations are not present, because three of the commentators are not in this dataset (Cho Lee, Jennings, Kapon).

Network showing similarities among the quality scores of 11 wine critics

Suckling, Falstaff and Spectator are closely associated, as expected from the results in the table, as are Parker and Leve. More interestingly, we can now evaluate three new commentators, all from France. Indeed, the four French commentators are closely associated in the graph (Revue de France, Bettane et Desseauve, Quarin, and Vinum Weinmagazin [from Switzerland]). Of these, only the Revue de France scores seem to be associated with any of the non-French commentators, having some connection to those of Robert Parker.

Thus, there is little commonality among the scores of different commentators, and this is especially true for Jancis Robinson. Furthermore, the four French commentators do seem to form a separate groups from the others. Perhaps it is relevant that these five people are the only ones in the dataset who use a 20-point quality scale rather than a 100-point scale.

Hill of Grace (Australia)

As an addendum, we can take a quick look at another single Australian wine that has a long record of critics' scores, following the Penfolds Grange used in the previous post.

Unlike Grange, the Henschke Hill of Grace is a single vineyard wine, made from c. 7 ha of shiraz. The oldest vines were planted in the 1860s; and in a good year there are about 2,000 cases of wine produced. The vintages date back to 1958, with four vintages when the wine was not made (leaving 50 released vintages for analysis). There are five commentators who have provided quality scores for almost all of these vintages, and two more who have covered at least one third of them.

As above, we can quantify the relationships among the scores using correlation analysis. This analysis reveals that the following percentages are held in common between the seven commentators pairwise. As above, values >60% are highlighted in green, those between 50 and 60% are in blue, and those <10% are in yellow.

Table showing correlations among the quality scores of 7 wine critics

As you can see, the correlations are extremely poor, except for those involving Huon Hooke, which are not quite so bad. None of the values exceeds 50%, and most are actually <10%. This means that there is very little agreement among the commentators in their quality scores.

This is the most extreme example of disagreement in quality scores that I have encountered.


The answer to the question posed in the title is: "a lot".

This broader analysis (six wines) confirms the results from the previous blog post (Poor correlation among critics' quality scores). The idea that wine commentators have some sort of consensus opinion with regard to wine quality is completely untenable, for all of the wines checked so far. In general, the agreement varies from 0–50%, so that the critics disagree more than they agree.

However, there are patterns of association among the commentators, so that their quality scores are not completely random. Unfortunately, this seems to be a relatively minor component of the data patterns. Nevertheless, the four French commentators do seem to have opinions about the French wines that differ from those of the other commentators.

Research Literature

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Monday, 27 March 2017

Vintage charts, and the variation within a wine-growing region

I noted in a previous blog post that not everyone is enamored of vintage charts (Modern wine vintage charts: pro or con?). Such charts provide a quality score for each wine vintage in some specified wine-making region.

One of the objections to these charts is that the ratings over simplify — there is quality variation between vineyards even within local areas, and this is not taken into account. That is, not all wine producers will produce high-quality wine in allegedly good vintages; and not all wine producers will produce poor-quality wine in allegedly bad vintages.

I thought that it might be interesting to illustrate this point in practice.

I will do this using some data for the wines of Bordeaux, taken from Michel Dovaz' book: Encyclopedia of the Great Wines of Bordeaux (1981; Julliard).

For each classified wine-producing chateau, Dovaz provides a wine quality score for each vintage from 1970-1980 (plus some others). The scores indicate the quality of each vintage relative to the other vintages from the same producer, with the best one scaled as a score of 10. This means that the relative quality of each vintage can be directly compared between producers, without any concern about whether some producers are better than others — all producers have at least one vintage with a score of 10. [Technically, the data have been standardized to the same maximum value.]

We can look at these data for each of the different areas within the Bordeaux region, to see how much local variation there is in success for each vintage. Do all of the producers have success, or lack of success, in the same years? If so, then a vintage chart would be a very convenient way to tell us which were the successful years.

The first graph covers the red wines of the commune of Margaux, north of the city of Bordeaux. Each colored line represents the quality scores of a single chateau, with the solid line being the average of the scores in each year.

Vintage variation between the chateau of the Margaux commune

This graph alone represents the general point rather well. The chateaux do follow a single main pattern through time, but there is great variation around the average quality score. In particular, the chateaux do not all follow the same rank order of vintage quality. For example, 1970 was a better vintage than 1971 for most of the chateaux, but for one of them it was the other way around. Alternatively, 1976 was a better vintage than 1977 for all of the chateaux, although it was much better for many of them but only a little bit better for others.

The next graph covers the red wines of the commune of St Julien, which is the next one north of Margaux.

Vintage variation between the chateau of the St Julien commune

There are fewer chateaux represented here, but there is even more variation among these chateaux than there was for the Margaux area. Note, however, that there was very little variation in the 1975 vintage compared to the others.

The next graph covers the red wines of the commune of Pauillac, further north.

Vintage variation between the chateau of the Pauillac commune

It is very similar to the previous graphs, being somewhat intermediate between the two of them.

There are too few classified chateaux in Saint-Estèphe to plot a worthwhile graph. So, we now move on to the area south of Bordeaux; and the next graph covers the red wines of the Graves region. There are too few Graves white wines to plot a worthwhile graph.

Vintage variation between the red-wine chateau of Graves

There are also few chateaux represented here. Note that for the first three vintages there is actually not much variation among the chateaux, but this changes for the rest of the decade, especially 1974.

The next graph covers the red wines of Saint Émilion, which is on the Right Bank of the Bordeaux region, rather than the Left. The adjacent area of Pomerol has data for only one chateau, and so it is included here, as well.

Vintage variation between the chateau of St Emilion

Clearly, the patterns of within-vintage variation are much the same for the Right Bank as for the Left. That is, not all of the chateaux follow the average pattern of variation, but most do, even though there is considerable variation among them.

Next, we can move on to Sauternes, the most famous white-wine region of Bordeaux, which makes very sweet wines.

Vintage variation between the chateau of Sauternes

This is the most expressive graph of all, regarding within-vintage variation. The making of high-quality sweet wines requires that the grapes be infected with Noble Rot (a fungus), and this process relies on very specific weather patterns. There were a number of years in the 1970s when the wine was deemed by a number of chateaux to be not worth releasing (scored 0 in the graph). Only in 1970 and 1975 did most of the chateaux produce high-quality wines.

Clearly, a vintage chart for Sauternes is not necessarily a reliable indicator of vintage quality. On the other hand, for the red wines shown in all of the previous graphs, such a chart would be useful in general. It would not, however, be a substitute for more detailed knowledge about each chateau.

Finally, lest we think that the results above are unique to the scoring system of Michel Dovaz, or are unique to the particular decade concerned, we could look at an independent source of data. The final graph shows the vintage quality scores from the Wine Spectator magazine, for the four "first growths" of the Médoc, covering the subsequent 33 years.

Even for these restricted chateaux, the within-vintage variation is large — the 1992 vintage was particularly variable. Note, however, that in this case the data have not been standardized, so that the within-year variation includes intrinsic variation in quality between the chateaux themselves (which may be small!).