Exam 11: Designing, Conducting, Analyzing, and Interpreting Experiments With More Than Two Groups

Latitia conducted an experiment in which all the men watched an aggressive television program, and all the women watched a non-aggressive television program. Her results showed that people who watched the aggressive program were later more aggressive than people who watched the non-aggressive program. She concludes that aggressive television programming is detrimental. What is the biggest problem in Latitia's experiment?

A researcher was interested in determining the effectiveness of humanistic therapy for alleviating depression. He administered a depression inventory to a sample of clients with depression on three occasions: before therapy started, two months after therapy began, and four months into therapy. Depression scores could range from 1 (not at all depressed) to 15 (extremely depressed). GROUP MEAN STD DEV STD ERROR 1 (Time 1) 10 13.50 1.58 0.50 2 (Time 2) 10 9.40 2.88 0.91 3 (Time 3) 10 7.30 4.06 1.28 $\text { ONEWAY ANOVA: DEPRESSION by TIME (CORR SAMP) }$ SUM OF MEAN SOURCE SQUARES DF SQUARES F RATIO PROB. TIME 198.87 2 99.43 18.43 .000 SUBJECTS 147.88 9 16.43 185.04 .000 WITHIN CELLS 97.13 18 5.40 TOTAL 443.88 29 POST HOC TEST: Tukey-HSD with significance level .05 * Indicates significant differences shown for pairings G G G r r r p p p 1 2 3 Mean TIME 13.50 Grp 1 9.40 Grp 2 7.30 Grp 3 -This is a correlated groups design. How do you know?

Source tables isolate the different sources of _________ in the data.

A multiple-group experiment often consists of

Noah conducts a study where the between-groups degrees of freedom is equal to 3 and the total degrees of freedom is equal to 50. What is the within-groups degrees of freedom?

Suppose you conduct a study and analyze the dataset two different ways: once as a one-way ANOVA for independent groups and once as a one-way ANOVA for correlated groups (note that in real life you would never do this!). What differences would you expect to see in the dataset?

A statistical test used to analyze data from an experiment with one independent variable that has three or more groups is known as a

Examine the Measures section on p. 382 of the article. What is the scale of measurement for the muscularity variable? What is the scale of measurement for the hair color variable?

Which of the following is a disadvantage of using natural sets in a multiple-group experiment?

Confidence intervals provide

Describe the multiple-independent groups design. How does the multiple-independent groups design utilize random assignment?

Questions refer to Table 11-2. In this study, 10 children completed a survey regarding their impressions of smokers at age 8 and then again at age 10 and 12. Scores could range from 1 (extreme negative impression of smokers) to 20 (extreme positive impression of smokers). Table 11-2 GROUP MEAN STD DEV STD ERROR 1 (AGE 8) 10 9.70 5.89 1.86 2 (AGE 10) 10 10.40 5.58 1.76 3 (AGE 12) 10 11.80 5.94 1.88 ONEWAY ANOVA: SMOKING by AGE (CORR SAMP) SUM OF MEAN SOURCE SQUARES DF SQUARES F RATIO PROB. AGE 22.87 2 11.43 6.76 .006 SUBJECTS 879.63 9 97.74 34.71 .000 WITHIN CELLS 30.47 18 1.69 TOTAL 932.97 29 POST HOC TEST: Tukey-HSD with significance level .05 * Indicates significant differences shown for pairings 1 2 3 Mean 9.70 Grp 1 10.40 Grp 2 11.80 Grp 3 -Consult Table 11-2. What kind of statistical analysis was conducted?

Researchers form ________ sets by measuring participants on some variable that will affect their performance on the DV.

Miguel conducts a study in which he compares the effectiveness of behavioral therapy, cognitive therapy, humanistic therapy, and psychodynamic therapy to treat phobias. In this study, the independent variable is _________ and it has ____ level(s).

An experiment in which an extraneous variable varies systematically with the IV is a(n) ________ experiment.

A researcher was interested in determining the effectiveness of humanistic therapy for alleviating depression. He administered a depression inventory to a sample of clients with depression on three occasions: before therapy started, two months after therapy began, and four months into therapy. Depression scores could range from 1 (not at all depressed) to 15 (extremely depressed). GROUP MEAN STD DEV STD ERROR 1 (Time 1) 10 13.50 1.58 0.50 2 (Time 2) 10 9.40 2.88 0.91 3 (Time 3) 10 7.30 4.06 1.28 $\text { ONEWAY ANOVA: DEPRESSION by TIME (CORR SAMP) }$ SUM OF MEAN SOURCE SQUARES DF SQUARES F RATIO PROB. TIME 198.87 2 99.43 18.43 .000 SUBJECTS 147.88 9 16.43 185.04 .000 WITHIN CELLS 97.13 18 5.40 TOTAL 443.88 29 POST HOC TEST: Tukey-HSD with significance level .05 * Indicates significant differences shown for pairings G G G r r r p p p 1 2 3 Mean TIME 13.50 Grp 1 9.40 Grp 2 7.30 Grp 3 -Write an APA-format conclusion for these results.

Individual differences among people in each group in a multiple-group experiment represent _________ variability.

Which of the following is a practical consideration in a multiple-independent-groups design?

In an ANOVA source table, what is the difference between sum of squares and mean squares?

Lauren conducts an experiment with three independent groups and 12 participants in each group. The total degrees of freedom would equal