In this study, the professor asked 15 students in his Introductory Psychology class to volunteer to take the smart pill at the start of the semester. The other 15 students in the class who did not volunteer did not take the pill. This was not random assignment because this subject was not an unbiased division, and the professor didn’t create equal groups; therefore, it could affect the result. In general, volunteers do better than non-volunteers because volunteers have more motivation than the people who didn’t volunteer. For example, in the “tutoring study”, people who signed up for tutoring were doing much better than the people who did not sign up for tutoring because the people who sign up care about their grade; on the other hand, the people who did not sign up don’t care and don’t want to improve their grade. As a result, the professor should have used a computer and put all the students’ names in to choose the people who take the pill who don’t.
There also a problem with representative sample. In his “smart pill” psychological research, he only chose 30 students to join this experiment. 30 people are small amount of population, and that’s too small of a sample size; therefore, this study is not representative. When people want to research a study, they should ensure that the study is a true reflection of the large population to which conclusions supposedly would apply because there are many students in a college: the students with art major, music major, and finance major or so on, but the professor only chose the students who are from his Introductory Psychology class. As a result, there is a big problem with representative sample. However, he should have randomly chosen a large group of students who have different majors, from different grade, or with different races to participate in this study.
Moreover, the professor graded all the exams and essays assigned to all students in the class to get their GPA in the end of the semester.