A researcher wants to see if watching a violent movie leads to more aggressive behavior in preschool children

How should the researcher proceed? Be sure to discuss sampling, assignment to conditions, and choice of independent and dependent variables.
What will be an ideal response?

A good answer will be similar to the following:
The researcher could use an experimental design. The participants should be a sample of preschool children who are similar in social class, IQ, etc. to the population of interest (representative sampling). These children would be assigned randomly to one of two experimental conditions. In one condition, children would see a movie that contained many violent acts. In the other condition, children would see a movie about sharing that contained no violent acts. The type of movie that the children watched is the independent variable. After watching the movie, the children would be allowed to play in a room with toys. Structured observation would be used to determine if the amount of aggressive behavior, while playing was related to the type of movie that the children had watched. Aggressive behavior while playing (e.g., hitting, kicking, punching) is the dependent variable.