A Note on a Test for the Sum of Ranksums

In wine tastings, in which several tasters (judges) taste several wines, it is important to insure objectivity to the extent possible. This is usually accomplished by holding the tasting “blind,” i.e., covering the bottles so that the tasters do not know which wine is in which bottle. At some agreed upon point in the proceedings, the tasters reveal what they think about the various bottles. Ideally, this revelation would take place by secret ballot, lest a taster's choices be influenced by what he or she hears another taster say. But in any event, there are two standard ways of rating the wines. The older method is to assign them “grades” on a scale of, say, up to 100 points (Parker) or up to 20 points as in the famous face-off between California wines and French Bordeaux wines in 1976 (see Ashenfelter et al., 2007). As Ashenfelter at al. point out, this has the distinct disadvantage that a judge with greater dispersion in his or her grades will have a greater influence on the average score that each wine achieves.