Ninth Edition CoverGraziano & Raulin
Research Methods (9th edition)

Chapter 8 Exercises
Hypothesis Testing, Validity,
and Threats to Validity

The following exercises are designed to give you hands-on practice of the skills learned in this chapter.

  1. For the following statements of the problem, list at least three specific research hypotheses.
    (a) What effect does worker participation in the decision-making processes have on worker morale and productivity?
    (b) What is the emotional impact on a woman of having an abortion?
    (c) How do ten-year-old boys and girls differ in their social relationships with people?
    (d) How does cocaine affect performance and motivation in laboratory animals?
    (e) Are certain types of words easier to memorize than other types of words?
    (f) How do depressed individuals differ from non-depressed individuals in their views about the future?

  2. Listed below are a number of brief descriptions of research studies. Identify possible confounding variables in these studies.
    (a) After careful observation, a teacher finds that there are certain times of day during which the students tend to be less attentive and more disruptive. The teacher concludes that there must be some aspect of the diurnal (daily) cycle for children that accounts for this behavior.
    (b) After a particularly bad quarter in terms of shoplifting, the manager of a department store decides to purchase a service that provides music with a subliminal message not to steal. The manager kicks off the program, which has been reported to be quite successful with other stores, by telling the employees why the program was instituted, how it will work, and that management will be evaluating how effective the program is over the next three months. The data for the first three-month period indicates a drop of 14.2 percent in shoplifting over the previous quarter.
    (c) The army is interested in the relative adjustment of its male and female recruits. In an initial study, 100 randomly selected male recruits and 100 randomly selected female recruits are rated on a number of variables (general adjustment, performance under pressure, and overall capacity) by the drill sergeants responsible for the recruits' training.

  3. Give at least three examples of each of the confounding variables listed below. It is best to choose examples from different types of studies to make sure that you truly understand each confounding variable. The confounding variables are: maturation, history, testing, instrumentation, regression to the mean, selection, attrition, diffusion of treatment, and participant effects.

  4. Think of five or six experimental research ideas. Create them or obtain them from published reports of studies. For each of these research ideas:
    (a) Develop a clear statement of a problem.
    (b)     Identify and operationally define the variables suggested by the problem statement.
    (c) Combine the problem statement with the operational definitions into a specific prediction and state the research hypothesis.

  5. Take the problem statements you developed in the preceding exercise and develop different operational definitions. Then develop several research hypotheses that are different from those developed in the preceding exercise. Why is it important to be able to do this in research?