I was reading through Andy Field's Discovering Statistics with SPSS. Following ANOVA, he ran several post-hoc tests.

When he described how to report the planned contrast and post-hoc results, he wrote this:

“Planned contrasts revealed that having any dose of Viagra significantly increased libido compared to having a placebo, t(12) = 2.47, p =.029, r =.58, but having a high dose did not significantly increase libido compared to having a low dose, t(12) = 2.03, p =.065, r =.51.”

Where did the r come from??