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The Application of Rasch Scaling to Wine Judging


Murray Thompson
Flinders University School of Education
dtmt@senet.com.au

 

 

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Abstract

The training of judges in sport and in industry is a challenging educational problem and recent developments in educational measurement can contribute to the resolution of this problem. The results of the judging of 98 wines from one class of a prominent Australian wine show were analysed using Rasch scaling. The raw scores were out of 20, graduated in steps of half a point, giving a total of 41 different scores. It was necessary to reduce this scale to an eight point scale, making all scores below 12.5 zero and compressing the remaining scores into seven scores from one to seven with each score combining two of the raw scores. It was found that this compression process does not adversely affect the analysis. This suggests that the traditional judging process tries to apply too fine a scoring system.

Two programs were used to estimate the harshness of the judges and the level of the wines. They were the Quest program and the RUMM program. It was found that there was a good fit to the Rasch model and useful, but some conceptually different information was derived from both the Quest and the RUMM programs. It was therefore possible to put the quality levels of the wines and the harshness of the judges on the one scale and make useful observations about the harshness and consistency of each of the judges which should prove useful feedback for the training and on-going professional development of wine judges. The RUMM program in particular offers very useful feedback to judges that shows just how they are awarding their grades along the continuum.

A means of reducing the total number of wines to be tasted by each judge was explored and it was found that the Rasch scaling procedure could be used to reduce the total tasting load on judges. Comparison of the raw scores the Quest and the RUMM showed very high correlations, with evidence of a greater spread of the Quest scores than the RUMM scores.

Wine judging, Rasch scaling, Quest, RUMM, consistency

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Thompson, M. (2003) The Application of Rasch Scaling to Wine Judging. International Education Journal, 4 (3), 201-223.
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