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

Participants who receive the IV are referred to as the _________ group.

Examine the results in Table 1 on p. 384 of the article. Do these results come from an independent-groups design or a correlated-groups design? How do you know?

A mean square is similar to

In the following study, participants were randomly assigned to receive humanistic therapy, psychodynamic therapy, or behavioral therapy for their depression. Six months after therapy ended, participants' levels of depression were rated on a Likert scale from 1 (not at all depressed) to 15 (extremely depressed). GROUP N MEAN STD DEV STD ERROR 1 (humanistic) 10 5.40 2.17 0.69 2 (psychodynamic) 10 7.50 2.84 0.90 3 (behavioral) 10 5.60 3.13 0.99 ONEWAY ANOVA: THERAPY bY DEPRESSION SUM OF MEAN SOURCE SQUARES DF SQUARES F RATIO PROB. BETWEEN GROUPS 26.87 2 13.73 1.78 .187 WTHIN GROUPS 203.30 27 7.53 TOTAL 230.17 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 THERAPY 5.40 Grp 1 7.50 Grp 2 5.60 Grp 3 -What is the scale of measurement for the dependent variable?

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 11-1. Which of the following is the best-written interpretation of the data?

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 -What kind of statistical analysis was conducted?

What is the purpose of post hoc comparisons?

Examine the results in Table 1 on p. 384 of the article. In APA-format, explain (in words) the results for Weight (M).

In the following study, participants were randomly assigned to receive humanistic therapy, psychodynamic therapy, or behavioral therapy for their depression. Six months after therapy ended, participants' levels of depression were rated on a Likert scale from 1 (not at all depressed) to 15 (extremely depressed). GROUP N MEAN STD DEV STD ERROR 1 (humanistic) 10 5.40 2.17 0.69 2 (psychodynamic) 10 7.50 2.84 0.90 3 (behavioral) 10 5.60 3.13 0.99 ONEWAY ANOVA: THERAPY bY DEPRESSION SUM OF MEAN SOURCE SQUARES DF SQUARES F RATIO PROB. BETWEEN GROUPS 26.87 2 13.73 1.78 .187 WTHIN GROUPS 203.30 27 7.53 TOTAL 230.17 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 THERAPY 5.40 Grp 1 7.50 Grp 2 5.60 Grp 3 -How could you change this experiment to be a matched sets design?

Examine the results in Table 1 on p. 384 of the article. In APA-format, explain (in words) the results for Muscularity (M).

What happens when we match participants on a variable that is unrelated to the dependent variable?

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. The p-value for age is ______ than .05; therefore, the results of the statistical analysis _____ significant.

Which of the following is NOT a way to create correlated groups?

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 11-1. The independent variable in this study is __________ and the dependent variable in this study is ____________.

In the following study, participants were randomly assigned to receive humanistic therapy, psychodynamic therapy, or behavioral therapy for their depression. Six months after therapy ended, participants' levels of depression were rated on a Likert scale from 1 (not at all depressed) to 15 (extremely depressed). GROUP N MEAN STD DEV STD ERROR 1 (humanistic) 10 5.40 2.17 0.69 2 (psychodynamic) 10 7.50 2.84 0.90 3 (behavioral) 10 5.60 3.13 0.99 ONEWAY ANOVA: THERAPY bY DEPRESSION SUM OF MEAN SOURCE SQUARES DF SQUARES F RATIO PROB. BETWEEN GROUPS 26.87 2 13.73 1.78 .187 WTHIN GROUPS 203.30 27 7.53 TOTAL 230.17 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 THERAPY 5.40 Grp 1 7.50 Grp 2 5.60 Grp 3 -Is this a true experiment or an ex post facto study? How do you know?

A significant effect in an ANOVA occurs when the probability value is

Examine the results in Table 1 on p. 384 of the article. Why did the authors analyze the data using an ANOVA instead of a t test?

The ANOVA formula is best conceptualized as:

Describe the natural sets approach to creating multiple-correlated groups and give an example.

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. Why are the degrees of freedom for the age variable equal to 2?