Interpolate NA values?

The proper way to do this statistically and still get valid confidence intervals is to use Multiple Imputation. See Rubin's classic book, and there's an excellent R package for this (mi).

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.