In terms of case choice, Gary King, Robert Keohane, and Sidney Verba alert towards "selecting about the dependent variable". They argue for example that scientists are unable to make valid causal inferences about war outbreaks by only taking a look at instances in which war did take place (the researcher https://griffintcped.thezenweb.com/5-tips-about-case-study-help-you-can-use-today-71400350