TABLE 4.

Correlations between shape characteristics of cells cultured in serum/LIF medium.

Variable Coefficient in PC1	Feret ratio −0.480	Circularity 0.521	Phase brightness 0.527	Area −0.470
Area	R = 0.195 p = 0.076	R = 0.489 p < 0.005	R = −0.765 p < 0.005	-
Phase Brightness	R = −0.669 p < 0.005	R = 0.770 p < 0.005	-	-
Circularity	R = −0.770 p < 0.005	-	-	-

Rex1-GFPd2 cells growing on gelatin. Correlations are assessed using Pearson’s R, where R gives the strength of the correlation from −1 to 1 and p indicates the probability of the null hypothesis that this R value arose by chance. There are strong correlations between the variables used to indicate cell shape, reflecting causal relationships. However, these causal links are not so strong that any two of these variables are mutually redundant.