ABSTRACT
A classic, simple experiment consists of two groups that are given different treatments. Your first obligation under "Procedures" is to describe how individuals will arrive at their group membership. If they will be assigned at random to groups, which is highly desirable, you should explicitly say so. On the other hand, if they are already in groups (such as students already enrolled in one high school to be compared with those enrolled in another one), this should be stated and any information on their comparability should be provided. For instance, are the achievement levels at the two high schools comparable? Do the students in the two schools come from similar socioeconomic levels?
