WINETASTER ON 04/20/09 WITH 6 JUDGES AND 8 WINES BASED ON RANKS, IDENT=N Copyright (c) 1995-2009 Richard E. Quandt, V. 1.65
A Tasting of Recent Syrah (Shiraz) Wines
FLIGHT 1: Number of Judges = 6 Number of Wines = 8
Identification of the Wine: The judges' overall ranking:
Wine A is Greenock Creek Alice Vineyard 2005 (Australia)........ 2nd place Wine B is Amayna 2007 (Chile) ........ 7th place Wine C is St. Joseph Offerus 2005 (Rhone) ........ 8th place Wine D is Dunham Columbia Valley 2005 (Washington State)........ 1st place Wine E is Mulderbosch Shiraz 2003 (South Africa) tied for 4th place Wine F is Gramercy,Lagniappe,Columbia Val.2005(Washington S)tied for 4th place Wine G is Salomon Finiss River Alttus 2001 (Australia) ........ 3rd place Wine H is Ojai Roll Ranch 2003 (California) ........ 6th place
The Judges's Rankings
Judge Wine -> A B C D E F G H John 1. 6. 7. 2. 8. 4. 5. 3. Bob 1. 8. 7. 2. 6. 3. 5. 4. Chris 4. 6. 5. 1. 2. 8. 3. 7. Mike 6. 7. 8. 2. 5. 1. 3. 4. Burt 5. 8. 7. 1. 2. 3. 4. 6. Dick 1. 3. 7. 5. 2. 6. 4. 8.
Table of Votes Against Wine -> A B C D E F G H
Group Ranking -> 2 7 8 1 4 4 3 6 Votes Against -> 18 38 41 13 25 25 24 32
( 6 is the best possible, 48 is the worst)
Here is a measure of the correlation in the preferences of the judges which ranges between 1.0 (perfect correlation) and 0.0 (no correlation):
W = 0.4206
The probability that random chance could be responsible for this correlation is quite small, 0.0136. Most analysts would say that unless this probability is less than 0.1, the judges' preferences are not strongly related. We now analyze how each taster's preferences are correlated with the group preference. A correlation of 1.0 means that the taster's preferences are a perfect predictor of the group's preferences. A 0.0 means no correlation, while a -1.0 means that the taster has the reverse ranking of the group. This is measured by the correlation R.
Correlation Between the Ranks of Each Person With the Average Ranking of Others (R) and with the Price of the Wines
Name of Person Correlation R Correlation Price Bob 0.7545 0.3473 Burt 0.7381 0.4671 Mike 0.5000 0.0479 John 0.4431 0.2156 Chris 0.4048 0.4791 Dick 0.2381 0.0120
The wines were preferred by the judges in the following order. When the preferences of the judges are strong enough to permit meaningful differentiation among the wines, they are separated by -------------------- and are judged to be significantly different.
1. ........ 1st place Wine D is Dunham Columbia Valley 2005 --------------------------------------------------- 2. ........ 2nd place Wine A is Greencock Creek Alice Vineyard 200 3. ........ 3rd place Wine G is Salomon Finiss River Alttus 2001 4. tied for 4th place Wine F is Gramercy Cellars,Lagniappe,Columbia Val. 2005 5. tied for 4th place Wine E is Mulderbosch Shiraz 2003 6. ........ 6th place Wine H is Ojai Roll Ranch 2003 --------------------------------------------------- 7. ........ 7th place Wine B is Amayna 2007 8. ........ 8th place Wine C is St. Joseph Offerus 2005 We now test whether the ranksums AS A WHOLE provide a significant ordering. The Friedman Chi-square value is 17.6667. The probability that this could happen by chance is 0.0136
We now test whether the group ranking of wines is correlated with the prices of the wines. The rank correlation between them is 0.3072. At the 10% level of significance this would have to exceed the critical value of 0.5240 to be significant.
We now undertake a more detailed examination of the pair-wise rank correla- tions that exist between pairs of judges. First, we present a table in which you can find the correlation for any pair of judges, by finding one of the names in the left hand margin and the other name on top of a column. A second table arranges these correlations in descending order and marks which is significantly positive significantly negative, or not significant. This may allow you to find clusters of judges whose rankings were particularly similar or particularly dissimilar. Pairwise Rank Correlations Correlations must exceed in absolute value 0.74 for significance at the 0.05 level and must exceed 0.64 for significance at the 0.1 level John Bob Chris John 1.000 0.881 -0.024 Bob 0.881 1.000 0.143 Chris -0.024 0.143 1.000 Mike 0.405 0.571 0.024 Burt 0.190 0.548 0.571 Dick 0.000 0.095 0.476 Mike Burt Dick John 0.405 0.190 0.000 Bob 0.571 0.548 0.095 Chris 0.024 0.571 0.476 Mike 1.000 0.738 -0.214 Burt 0.738 1.000 0.167 Dick -0.214 0.167 1.000 Pairwise correlations in descending order 0.881 John and Bob Significantly positive 0.738 Mike and Burt Significantly positive 0.571 Chris and Burt Not significant 0.571 Bob and Mike Not significant 0.548 Bob and Burt Not significant 0.476 Chris and Dick Not significant 0.405 John and Mike Not significant 0.190 John and Burt Not significant 0.167 Burt and Dick Not significant 0.143 Bob and Chris Not significant 0.095 Bob and Dick Not significant 0.024 Chris and Mike Not significant 0.000 John and Dick Not significant -0.024 John and Chris Not significant -0.214 Mike and Dick Not significant
Comments: All eight of the wines were good and ready to drink in spite of their relative youth. Dunham's is to be congratulated for winning in a strong field. On the whole, the wines were very alcoholic, ranging from 13.5 to 17%. There was substantial group agreement as to the rank ordering of the wines, and we all came away from the tasting with enhanced respect for the Syrah grape and its ability to produce good wines on all continents.
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