Chapter 14 Quiz Review

One advantage of using repeated-measures designs rather than standard between-subjects designs is that:

• The error SS is often smaller in repeated-measures thereby increasing power.

• Because outcome variables are correlated in repeated measures, the explained SS is higher.

• RM ANOVA usually has a lower risk of Type I error.

• It does not have to meet all of the assumptions given for between subjects designs.

Which is true regarding the effect size in repeated-measures ANOVA?

• It is calculated using Wilk's lambda (Λ).

• Because error variance is usually smaller, the effect size is usually smaller

• It is determined by the change in R2 across each treatment level

• η2 is calculated with the variance of person effects partialled out

Suppose a researcher is measuring the degree of frustration in infants on three novel tasks, A, B, and C. The tasks were presented in order (A then B then C), the frustration measure was taken immediately after each task, and infants were given a 3-minute "cooling down" period between tasks. If repeated-measures ANOVA showed the highest frustration levels on C and lowest on A, what could be a potential confound?

• Carryover Effects

• Fixed-Effects Model

• Task Complexity

• Sensitization

Answer explanation

A carryover effect is an effect of being tested in one condition on participants' behavior in later conditions. Since the groups differed based on time of measure, this would create a confound, produced by a carryover effect.

When all other factors are the same, which of the following statistical tests typically has the least sampling error?

• Independent samples t-test

• Matched samples t-test

• Repeated Measures ANOVA

• One-sample t-test

Researchers had 6 participants follow 3 different diets over a period of 1 year. Each diet lasted 4 months. Participants then were measured on the amount of weight loss after each type of diet. What is the total number of scores provided by the participants?

• 18

• 24

• 12

• 6

Answer explanation

In the study, there were only 6 participants. The participants were given a different diet every 4 months to track weight loss. Since there was 3 diets total, that means the 6 participants had to report their scores 3 different times, mathematically expressed like: 3 x 6 = 18. Therefore, 18 scores were reported within te study.

Researchers had 6 participants follow 3 different diets over a period of 1 year. Each diet lasted 4 months. Participants then were measured on the amount of weight loss after each type of diet. What is a in this experiment?

• 3

• 6

• 4

• 1

Answer explanation

"a" represents the number of conditions within an experiment. Since we have 3 different diets, we have 3 different conditions.

For a study of 3 different treatments for social phobia, researchers had 7 participants try a new treatment every 4 months over a period of a year and measured their anxiety levels in regard to social situations. Results showed F (2, 12) = 10.80, p = .02, α = .05. What is the df_total?

• 21

• 20

• 12

• 14

Answer explanation

Recall that df_total in an RM ANOVA relies on the total number of SCORES from participants. Since there were 7 participants being tested over 3 conditions, that would produce a total of 21 responses (7 x 3 = 21). Now, we must take this value and subtract 1 degree of freedom since we're still dealing with only one sample: 21 - 1 = 20.

Which of the following is a source of variability that contributes to within-treatment variability for an RM ANOVA study?

• Individual Differences

• Sensitization

• Treatment Effect

• Experimentwise Alpha Level

What goes into the denominator when solving for our F-ratio in a Repeated Measures ANOVA?

• MS_{Between Treatments}

• MS_Error

• MS_{Within Treatments}

• MS_{Between Subjects}

We have two new variances we must solve for in this chapter, including Error Variance and _____

• Between Treatments Variance

• Between Subjects Variance

• Residual Variance

• Pooled Variance