To qualify as a true experiment, a research study requires the manipulation of at least one variable. The fact that some variables cannot (or should not) be manipulated limits the topics that can be investigated easily with an experimental study.
If you were conducting a PsycINFO search for each of the following subjects, indicate which subjects are more likely to produce examples of true experiments and which are less likely. In each case, explain your answer.
a. adolescent self-esteem
b. anorexia treatment
c. mathematics instruction
d. alcohol and academic performance.