# Point-Biserial Correlation (r) for non homogeneous independent samples

I am performing an independent t-test, in which the independent variable is the "group" which has two values A and B representing an approach the participants used, and the dependent variable is a metric for accuracy "Recall" which has numeric values ranging from 0 to 100. Total number of participants is 18 (9 in each group) randomly assigned to the groups.

What is the formula I should use to use in calculating the effect size in terms of the Point-Biserial Correlation (r), knowing that the two independent variables are non homogeneous according to Levene's test?

• What variable(s) are ordinal - DV or IV? You say two independent variables what do you mean? "Independent T-test" is done with one grouping independent variable with 2 groups. Feb 3, 2016 at 20:44
• Hello ttnphns, the IV is the "group" which has two values A and B representing an approach they used, the DV is metric for accuracy "Recall" which has numeric values ranging from 0 to 100.
– H.A.
Feb 4, 2016 at 11:09
• How can you possibly calculate a correlation coefficient on independent data? Correlation measures are for pairs/dependent groups. Jun 30, 2018 at 0:14