I have been working with Univariate (ANCOVA) with one dependent variable, one independent variable and one covariate for a client. The client wants information about the effect size, in particular Cohen's d.
SPSS gives information regarding the calculation. It mentions that:
"If the model is a Univariate ANOVA with two groups, and the number of observations in each group is equal" Cohen can be calculated from the partial eta square.
The problem is that the number of observations is different for each group.
Can I still use the approach suggested by "IBM SPSS Support" or do I need to use a different approach?
Thank you!