This function calculates ANOVA F-values (type I sum of squares) for all
identity traits in dataset along with its significance. Each trait is used as
dependent and identity code as independent variable. Reference: e.g., Miller, D. B. (1978). Species-typical and individually distinctive acoustic features of crow calls of red jungle fowl. Zeitschrift Fur Tierpsychologie-Journal of Comparative Ethology, 47, 182<U+2013>193.