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Discrimination vs. representativeness of testers 

From Biplot Analysis, click Discrimination vs. representativeness. The following will appear on the biplot:

• The vectors for the testers;
• A small red circle indicating the position of the average tester, which is defined by the average PC1 and PC2 scores across all environments. This average environment can be regarded as a virtual environment;
• a thick red line that passes through the biplot origin and the average environment, referred to as the average-tester axis;
• a red arrow pointing to the average environment from the biplot origin;

Interpretation:

• The vector length of a tester represents its discriminating ability. Thus testers 5 and 7 are the most discriminating testers.
• The angle between a tester and the average-tester axis represents the representativeness of the tester: the larger the angle, the less representative the tester. Thus testers 3 is most representative whereas tester 7 the least representative.
• An ideal tester should be both discriminating of the entries and representative of the average tester. See Rank testers relative to the ideal tester.. 

In Depth:

This function applies only to GGE biplots with certain data scaling methods.  Particularly, GGE biplot based on Standard Deviation scaled data does NOT have this interpretation.