I am analyzing student performance on a pre/post test designed to assess gains for a week long high school biology curriculum on natural selection.
After comparing pre/post performance using a variety of different metrics (test score, Rasch measure, chi-square per item) between the paired samples, I conducted an ANOVA to gauge whether there were differences between teachers. Two of the (seven) teachers are significantly different from the others (their students have drastically lower mean Rash measures and did worse overall), so I'd like to account for these differences in the analysis.
Is a nested ANOVA model appropriate here? I know nested models aren't in the SPSS dialogs, but I'm not much of a programmer and thus do not know what syntax to produce.
Moreover, each teacher has a different number of students. Would a random sample (ensuring the same amount from each teacher) be useful for paired comparisons of means (like pre vs. post), or does it not matter since it's a comparison of means between groups anyway?
Apologies for any obvious questions. Education is not my original field (I'm a bio-anthropologist), and it's been a bit since I took multivariate stats in grad school.