Anova Statistics

1.

Developmental psychologists study children at different ages. In this study, the children were tested three times, at ages 5, 6 and 7. At each age, they worked a set of 25 problems. Each problem was a measure of the child's understanding of the concept of conservation (the concept that quantity remains the same despite changes in shape). The scores below represent percentage correct on the set of 25 problems.

Calculate a repeated-measures ANOVA, Tukey HSD tests, and write an interpretation.

Age

Child 5 6 7

1	4	12	68
2	12	24	80
3	20	16	88
4	20	20	84

2.

Developmental psychologists study children at different ages. In this study, the children were tested three times, at ages 10, 11 and 12. At each age, they worked a set of 25 logic problems. The scores below represent percentage correct on the set of 25 problems. Calculate a repeated-measures ANOVA, Tukey HSD tests, and write an interpretation.

Age Child 10 11 12

1 0 8 40

2 8 12 36

3 12 24 36

4 16 20 48

3.

Drug testing often involves giving participants each of the several dosages as well as a placebo (an inert substance). In this study, the dependent variable was reaction time in hundredths of a second.

Calculate a repeated-measures ANOVA, Tukey HSD tests, and write an interpretation.

Dosage

Participant Placebo 15 mg 30 mg 60 mg

1	36	32	20	18
2	35	40	25	27
3	40	42	30	24

4.

Drug testing often involves giving participants each of the several dosages as well as a placebo (an inert substance). In this study, the dependent variable was a test that measured willingness to take risks (large scores mean more willingness). Calculate a repeated-measures ANOVA, Tukey HSD tests, and write an interpretation.

Dosage

Participant Placebo 15 mg 30 mg 60 mg

1	10	40	31	50
2	24	48	36	36
3	32	50	62	55

5.

There are many programs that seek to change behavior. One way to assess the effect of a program is to give a pretest, administer the program, and give a posttest. To really prove the lasting value of the program, however, a researcher must gather follow-up data some months later to see if the improvement seen at posttest has continued. In the scores below, larger numbers represent improved performance.

Analyze the data, compile it into a summary table, and make three HSD comparisons. Write an interpretation that describes the effect of the program.

Three data sets (labeled A, B, and C) are provided for problem 5.

Data Set A

Pretest Posttest One-year follow-up

Subject 1	10	28	21
Subject 2	13	27	24
Subject 3	17	36	26
Subject 4	18	31	20

Data Set B

Pretest Posttest One-year follow-up

Subject 1	9	23	18
Subject 2	13	27	24
Subject 3	17	36	26
Subject 4	18	31	20

Data Set C

Pretest Posttest One-year follow-up

Subject 1	10	28	21
Subject 2	13	27	24
Subject 3	17	36	26