For my master thesis I am facing some issues and I would appreciate some advice. I use Stata 16 for Mac. I need to use the principal component analysis to combine four components into one; colonial ties(binary;dummy), shared monetary union (binary;dummy variable), government effectiveness(continuous), voice and accountability (continuous). Now I also need to do a heckman test to control for a biased selection. I am not sure whether or not you can run a command first to do a PCA and then a heckman test? Is that possible? Which one to do first? I cannot find it anywhere and I truly hope someone can help me online! I do not have the database ready because I first want to check if this is possible. Every help is much much appreciated.