I self track partly to optimize intelligence and productivity. Cognitive tests are good proxy of both. I tried all the tests in "time of day" experiment at quantified-mind and many seem to test the same thing. I would like to select a smaller subset of them so that I am not retesting the same underlying abilities multiple times but ideally not miss any either. Are there any studies about correlation of such tests or even formal batteries that I could perform at home for little cost?