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

Chapter 9 Exercises
Controls to Reduce Threats to Validity

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

  1. For each of the following research areas, describe some of the general control procedures that you would likely wish to use.
    (a) The study of drug effects on eating behavior in laboratory animals.
    (b) Differences in response to frustration in male and female college students.
    (c) The impact of having the father present on social behavior in four-year-old children.
    (d) The difference between people with dependent personalities and people with passive-aggressive personalities in the way they respond to a frustrating situation.
    (e) The impact of having several people present on one's response to a personal challenge.

  2. For each of the research areas discussed in Question 1 above, describe some of the controls one might use to minimize the impact of subject and experimenter effects.

  3. Listed below are the IQ scores of 20 participants. In a study on reasoning styles, the researcher believes it is important to have groups that are comparable on IQ scores.
    108 132 94 69 83 94 98 121 102 114
    79 87 93 106 108 97 111 92 103 76
    (a) Using a table of random numbers, assign each of the 20 participants to one of two groups, with the proviso that there be exactly 10 participants per group. Use a free random assignment method. Compute the mean IQ in each of the two groups. Repeat this two additional times by starting at a different point in the random number table.
    (b) Now match all 20 participants in pairs based on their IQ. Using the matched random assignment method, create two groups of 10 participants each. Compute the mean IQ in each group. Repeat this process two additional times.
    (c) Compare how similar the groups are on IQ when using free random assignment versus matched random assignment (i.e., compare the results of a and b above).

  4. For each of the following independent variables, indicate the number of levels and identify each level:
    a.     We study the effects of bright and dark illumination on participants’ perception of stimuli.
    b.     We vary the amount of noise using four levels in a study of classroom behavior.
    c. A researcher compares children’s ability to solve riddles under different conditions. One group of children is given no extra clues, another group is given one extra clue, and a third group is given five extra clues.
    d. Five different kinds of pain relief medication are tested in a pharmaceutical laboratory.