# Effect Size Calculator for the T-Statistic

Instructions: This effect size calculator for the t-statistic allows you to compute the value of $$r^2$$ (r-squared) if you know the t-statistic ($$t$$) and the number of degrees of freedom ($$df$$):

T-statistic ($$t$$):
Degrees of Freedom (df):

## More About the Effect Size for the T-Statistic

The idea of the effect size is to measure the size of an effect, without getting inflated by the sample size(s), which happens with the traditional use of the p-value in hypothesis testing. One measure of the size of the effect is $$r^2$$ (r-squared), which is computed as

$r^2 = \frac{t^2}{t^2+df}$

The value of $$r^2$$ is interpreted as the proportion of variation in the dependent variable that is explained by the independent variable