Recommendations for Hart Banach

1. Carefully and clearly choose and define one or several variables that can directly reflect the research purpose. For example, if the purpose is to see whether students benefit from certain approach of teaching, then variables that measure students' performance would be good candidates.

2. Once the subjects (students) are voluntarily enrolled in the study, it's better to randomize them into control group and treatment group instead of grouping them according to certain criterion. It's also important to blind them to their grouping label.