This decision tree is a learning aid I designed which is in use at the University of Guelph for a class called "Quantification in Psychology".  This is an introductory statistics class.  Choosing the most appropriate hypothesis test for any particular study is key, and somewhat complex since there are a lot of variables that determine what kind of test will do the trick.  I used a colour coding system and boxes shaped to visually augment and represent the verbal content to make this complex flow chart as readable and memorable as possible.