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15 Examples 282Interpretation of resultsRecall that the researcher is interested in varietal tolerance to bloodworms. Thiscould be defined in various ways. One option is to consider the regression implicitin the variance structure for the trait by variety effects. The variance structurecan arise from a regression of treated variety effects on control effects, namelyu vt = βu vc + ɛwhere the slope β = σ vct /σ 2 v c. Tolerance can be defined in terms of the deviationsfrom regression, ɛ. Varieties with large positive deviations have greatest toleranceto bloodworms. Note that this is similar to the researcher’s original intentionsexcept that the regression has been conducted at the genotypic rather than thephenotypic level. In Figure 15.9 the BLUPs for treated have been plotted againstthe BLUPs for control for each variety and the fitted regression line (slope = 0.61)has been drawn. Varieties with large positive deviations from the regression lineinclude YRK3, Calrose, HR19 and WC1403.0.5BLUP regression residual0.0-0.5-2 -1 0 1 2 3control BLUPFigure 15.10: Estimated deviations from regression of treated on control for eachvariety plotted against estimate for control