I have a few quick questions regarding the beta image outputs from my analyses in SPM12. If I'm running a simple regression with one variable, there will be two beta images in the folder I conducted the analysis in. Is the first one (beta_001) the mean beta image and the second (beta_002) the beta image from the test variable?
Second, when running a two-sample t-test with no covariates there are also two beta images. Is the first one (beta_001) then the beta for the first group and the second one (beta_002) the beta for the second group? Or is one of the beta images a mean?