I am wanting to conduct several regression analyses – I am unsure what the procedure should be when doing this regarding data screening. This is mainly in concern with my sample; do I report my overall sample regardless of data screening and then, remove cases as needed for each model conducted? The issue with this is that the models would not really reflect the sample that was reported. Or do I keep screening until I am left with a sample that fits all regression models (i.e., no outliers etc that need to be deleted).
firs of all why you conduct several regression separately? to see the cumulative effect most researchers use multivariate regression. moreover check for assumptions of linear regression. if your objective is to identify the most influential variables you can use principal component analysis.