Table 5.

Prediction accuracy (correlation between observed and predicted phenotypes) for four breeding traits: tuber weight per plant (TW), tuber number per plant (TN), average weight per tuber (ATW) and host plant resistance to late blight (LB)

Training population	Test population	Breeding trait
		TW	TN	ATW	LB
T1-C	T1-D	0.088	–	0.101	0.29
T1-D	T1-C	0.069	–	0.080	0.31
T1-C*		0.130	0.070	0.337	0.25
T1-D*		0.300	0.260	0.182	0.16

Model validation was conducted on individuals divided by full-sib family or by randomly partitioned fivefold cross validation within each full-sib family. The symbol “-” indicates that the prediction accuracy for the trait was negative, i.e., prediction was not possible.

^*For the cross validation within the full-sib family, individuals were divided at random, mean prediction accuracies were estimated over 100 model runs.