GINI error analysis.

Locations where gene expression cannot be predicted easily. Red color indicates that the true gene expression was higher than predicted by the regression, while blue indicates that the true gene expression was lower than predicted by the regression. Note that since the difference in the true and predicted gene expressions is very small, the mean residue values were multiplied by 10 to improve the contrast of the image for visualization purposes. Thus, there is no systematic bias in the spatial locations where expression is hard to predict.