Cross-validation errors of the multivariate models. Cross-validation errors [Equation (4)] among the three multivariate models (MLR, RT, and ANN) and the third-order polynomial regression . The chosen optimal model for each of the three multivariate methods is labeled with enlarged solid symbols with "+" indicating one standard error of the CV errors. The linear model using the most contiguous hydrogen bond (by treating GC as 3 hydrogen bonds and AT as 2 hydrogen bonds as used in Wren et al.; labeled as contiguous HB) had comparable performance as the linear model using most contiguous base pair as the sole predictor (MLR when p = 1). The cross-validated variance of TY, labeled as "no predictors", is 1.43 ± 0.13. Regression tree with two variables, X11 and X4, outperformed the other multivariate and univariate models.