Two-Factor ANOVA

Two-Factor ANOVA

1. What is the dependent variable?

DV: passive avoidance.

2. What are the independent variables?

IV: Maternal diet. Levels: No alcohol, alcohol.

IV: age. Levels: adolescent, adult

3. State the three alternative hypotheses in words. State the alternative hypothesis of the interaction in terms of whether the effects of diet depend on age.

H1: Main effect of maternal diet is significant: There are significant differences in passive avoidance means between rats with a maternal diet with alcohol and rats with a maternal diet without alcohol ( or passive avoidance of rats with a maternal alcohol with alcohol is significantly different from passive avoidance of rats with a diet without alcohol).

H1: Main effect of age is significant: There are significant differences in passive avoidance means between adolescent and adult rats (or passive avoidance of adolescent rats is significantly different from the passive avoidance of adult rats)

H1: The diet by age interaction is significant: The effect of diet on passive avoidance depends on age: The effects of maternal diet on passive avoidance is significantly different in adolescent rats and adult rats.

4. Which two means are compared to determine whether there is a main effect of maternal diet?

  4.8 and 11

5. Which two means are compared to determine whether there is a main effect of age?

  9.6 and 6.2

6. Which of the following statements is TRUE

There are main effects of both maternal diet and age, and an interaction

7. Is the main effect of age significant? Provide F, df, p-value, and effect size (partial eta squared).

Yes, the main effect of age is significant because p is less than alpha, F (1,16) = 12.23, p = .003, η2 = .43.

8. If the main effect of age is significant, describe the main effect of age. Include the overall means and corresponding standard deviations in your description.

Main Effect of Age: Adolescent rats show significantly higher passive avoidance (M = 9.60, SD = 6.65) than adult rats (M = 6.20, SD = 2.04 ).

9. If there is a main effect of maternal diet, is the main effect of maternal diet significant? Why? Provide F-statistic, df of numerator, df of denominator, and p- value?

Yes, the main effect of maternal diet is significant because p is less than alpha, F(1,16) = 40.67, p = .0001, η2 = .71.

10. If the main effect of maternal diet is significant, describe the main effect of maternal diet. Include the overall means and corresponding standard deviations in your description.

Main Effect of Maternal Diet: Rats with a maternal alcohol diet show a significantly higher passive avoidance (M = 11.00, SD = 5.49 ), than rats without a maternal alcohol diet (M = 4.80 , SD = 1.81 ).

11.If there is an interaction, is the interaction significant? That is, does the effect of maternal diet on passive avoidance depends on the levels of age(i.e., on whether the rat is adolescent or adult)? Why? Provide F-statistic, df of the numerator, df of the denominator ,  and p-value.

The maternal diet by age interaction was significant because p is less than alpha, F(1,16)= 35.59, p=.0001

12.If the Age by Maternal Diet interaction is significant, describe the interaction. Include individual means and their corresponding standard deviations in your description.

Adolescent rats have higher passive avoidance when they have a maternal diet that includes alcohol (M= 15.60, SD= 2.881) than when they do not have a maternal diet that includes alcohol (M= 3.60, SD= 1.140). Adult rats also have higher passive avoidance when they have a maternal diet that includes alcohol(M = 6.4, SD = 6.4) than when the maternal diet does not include alcohol (M = 6, SD = 1.58). However, the difference in passive avoidance between the alcohol and no alcohol conditions is larger in adolescent rats than in adult rats.

13. Graph the interaction. On the “Category Axis” box put “maternal diet”. On the “Define Lines by” box put “age. Paste the graph into a word document and upload the file.

14. Report the results in APA

A two-factor ANOVA was conducted to examine the effects of maternal diet and age on passive avoidance. There were significant main effects of maternal diet, F(1,16) = 40.67, p=.0001, and of age F (1,16) = 12, 23, p= .003. The interaction between maternal diet and age was also significant, F(1,16) = 35.59, p=.0001. Adolescent rats have higher passive avoidance when they have a maternal diet that includes alcohol (M= 15.60, SD= 2.881) than when they do not have a maternal diet that includes alcohol (M= 3.60, SD= 1.140). Adult rats also have higher passive avoidance when they have a maternal diet that includes alcohol (M = 6.4, SD = 6.4) than when the maternal diet does not include alcohol (M = 6, SD = 1.58). However, the difference in passive avoidance between the alcohol and no alcohol conditions is larger in adolescent rats than in adult rats.