Hello! This app is great and I look forward to using it as a resource once I get a better handle on the app itself.
I feel like I have a pretty simple issue, but I didn't see other people asking about controlling variables with ANOVA.
I'm doing a national survey of marriage and family therapists and I'm having trouble getting a solid number on sample size. I have an DV measurement (21-item scale, Alpha=.88, M=97.8, SD=14) and a IV measurement (8-item scale, Alpha=.923, each item ranging from -5 to +5) with both scales already being psychometrically tested. I want to determine the amount of variance the IV has on the DV controlling for as many demographic constructs as possible. I'm looking to control at minimum for ethnicity, gender, and age ranges; with the hope for controlling for other demographics as well.
What am I missing or not understanding?
Thanks,
Daniel