For the following questions, choose the correct inferential statistical test that the researcher should use. Note that in all cases, assume that you meet the assumptions for the parametric test. Provide explanations for each choice!!

1. A researcher examined the effect of different kinds of music on general math ability. Forty-eight subjects were randomly assigned to do a series of math tasks under one of three conditions: 16 while listening to soft gentle music, 16 while listening to loud intense music, and 16 while in silence. The math quiz contained arithmetic, geometry, and word problems. There were 25 items that were 2 points each.

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2. A health psychologist conducted a study on the how the number of hours a person exercised each week relates to the number of days being sick per year. Participants were randomly selected from the community and provided self-reports through a series of questions on the topics of interest.

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3. A study was designed to test the effects of science fiction movies on participants' belief in the supernatural. A scale was designed to measure the degree that a subject believes in the supernatural (high scores indicate high levels of belief). Fifty-seven subjects, selected via random digit dialing (RDD) responded to the scale before and after watching Return of the Jedi, a popular science fiction movie.

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4. A director of a small psychotherapy clinic is trying to plan hiring of temporary staff to assist with intake. She is wondering if there was any difference in the use of the clinic during different seasons of the year. Last year, there were a total of 128 new clients. To see if there is a difference by season, she looks at how many clients previously enrolled during each season. Note: The data is inputted as two variables, season (winter, spring, summer, and fall) and intake (yes or no).

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5. A psychologist wants to know if a 6-month exercise training program affects blood pressure. The psychologist collects blood pressure data before the program, half-way through the program, and again at the end of the program.

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6. A researcher at a drug treatment center wanted to determine the best combination of treatments that would lead to more substance free days. This researcher believed there were two key factors in helping drug addiction: type of treatment (residential or outpatient) and type of counseling (cognitive-behavioral, psychodynamic, or client-centered). New clients enrolled at the center were randomly assigned to one of the six experimental groups. After 3 months of treatment, each client's symptoms were measured.

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7. A researcher in an organization wants to test whether their well-being program improves employee satisfaction at the organization. They randomly assign employees to either receive the well-being program or not. At the end of the year, the researcher examines how the program affected employee satisfaction.

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8. An educational psychologist is interested in understanding the extent to which first-year grades in college are predicted by such factors as standardized test scores, high school GPA, and participation in extracurricular activities.

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9. Imagine you are a researcher interested in sex differences in student's attitudes toward homosexuals. Specifically, you want to test the idea that women are more accepting of homosexuals and thus have more positive attitudes toward homosexuals than do men. You collect data from 10 men and 10 women using a scale that measures homophobia. Your data looks like this (note: larger scores equal more positive attitudes).

MEN WOMEN

2 5

4 5

6 6

8 8

1 9

2 9

5 4

9 2

10 7

2 6

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10. A researcher believes that recall of verbal material differs with the level of processing. He divided his subjects into three groups. In the low processing group, participants read each word and were instructed to count the number of letters in the word. In the medium processing group, participants were asked to read each word and think of a word that rhymed. In the high processing group, participants were asked to read each word and try to memorize it for later recall. Each group was allowed to read the list of 30 words three times, then they were asked to recall as many of the words on the list as possible. If the researcher wants to know whether the three groups have different amounts of recall, what type of statistical test should be used?

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11. A researcher is interested in testing two interventions designed to reduce racist graffiti in an inner city area. He recruited ten neighborhoods that have a problem with racist graffiti and asked assistants from the community to provide measures of the square feet of new racist graffiti each week. After four weeks of baseline recording, a six week sensitivity training workshop was begun in five of the ten neighborhoods and an advertising campaign was conducted in the other five neighborhoods. Community members continued to measure the extent of any new racist graffiti each week, yielding data from the 10 neighborhoods for 10 consecutive weeks, 4 prior to workshops and 6 after workshops began. The researcher wants to know if the interventions reduced the amount of new racist graffiti and if they differed in any effect. What statistical technique would you advise?

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12. A psychologist wants to investigate the relationship between stress and mental health during the first year of college. The researcher developed scales that measure 1) the frequency of stressful events, 2) the perceived importance of these events, 3) the desirability of such events, and 4) the impact of these events of the student. The researcher had 150 first year college students fill out this questionnaire as well as a Symptom Checklist, which is designed to assess the presence or absence of psychological disorders. What statistical procedure would help this researcher discover if psychological disorders can be predicted from the different aspects of stress that have been measured?

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13. A psychologist is interested in the relationship between job satisfaction and stress. Within a large corporation, the psychologist asked a random sample of workers two questions. The first question asked workers to rate their overall satisfaction with their job on a scale from 1 to 50. The second question asked the workers to rate their stress level during the past week on a scale from 1 to 50. What type of statistical test best assesses the relationship between job satisfaction and level of stress?

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14. An institutional researcher at a large university wants to compare the mathematical abilities of its male and female students. A researcher selects 100 men and 100 women at random from each of the four classes, and administers a standardized mathematics test. The men average 500 on the test, with a standard deviation of 120. The women average 450 on the test, with a standard deviation of 110. What test would be appropriate to determine whether the difference between men and women is real or due to chance variation?

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15. A psychologist is interested in attitudes towards the disabled. She believes that contact with someone who is disabled might have an effect on peoples' attitudes. To test her hypothesis, she measured attitudes toward the disabled both before and after contact with an individual in a wheelchair. What type of statistical test should she use to determine if contact with a disabled person changes peoples' attitudes toward the disabled?

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16. A psychologist is interested in whether or not handedness is related to gender. Specifically she wants to know if the percentage left-handed men in the population is different from the percentage of left-handed women. She collected data on handedness for 200 men and 200 women. What type of statistical test would be appropriate?

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17. A researcher is interested in the relationship between socio-economic status (SES) and domestic violence. She believes that there is a greater incidence of domestic violence in households below the poverty line. To assess this relationship, she surveys a random sample of American adults and asks two questions. First participants are asked to estimate their household income. Later in the survey participants are asked if there has been any physical violence between members of their household (Yes or No). How could the researcher determine whether there is a relationship between SES and incidence of domestic violence?

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