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

Groups of participants that are related in some way are known as _________ groups.

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 -This study is an independent groups design. How do you know?

Briefly describe the three strategies for creating multiple-correlated groups: (1) matched sets, (2) repeated measures, and (3) natural sets.

Describe ex post facto research. Give an example of a multiple-group ex post facto study.

_________ groups designs have decreased error variability compared to _____________ groups designs.

Compare and contrast the two-group design and the multiple-group designs. In what ways are they similar? In what ways are they different? Under what circumstances should you choose the multiple-group design over the two-group design? Under what circumstances should you choose the two-group design over the multiple-group design?

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 dependent variable in this study?

What is the formula for between-groups degrees of freedom?

Suppose you find an overall significant F ratio in your one-way ANOVA. What should you do next?

Which of the following is NOT a control procedure?

An experimental effect caused by expectation or suggestion rather than the IV is known as

Groups of participants that are formed by random assignment are known as _________ groups.

What is a placebo effect? Give an example of a multiple-group experiment in which the researcher tests for a placebo effect (e.g., the coffee example from the text).

Sum of squares refers to the

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

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 -Is this a two-group design or a multiple-group design? How do you know?

When you use _________, each participant must take place in all the various treatment conditions.

Hugh conducts an experiment with three independent groups and 20 participants in each group. The between-groups degrees of freedom would equal

Darryl conducts a study in which participants rate their liking for their professor on the first day of class, at midterm, and on the last day of class. Darryl has used which research design?

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 means are significantly different from each other?