A generally interesting study subject. But it seems not quite thought through. Projects might only invest in unit tests once a project exceeds a certain compl

A generally interesting study subject. But it seems not quite thought through. Projects might only invest in unit tests once a project exceeds a certain complexity, or has seen refactorings with age which made the need for tests clear. I'm not sure how to normalize properly, but maybe projects solving a similar problem could be compared. Like different ORMs or Databases or Kernels.