statistics homework

Research Methods in Psychology

Assignment 6

1. Read the experimental description below. Then answer the questions that follow.

Suppose you were doing a study to assess people’s reactions to persons with AIDS. You provide subjects with hypothetical scenarios in which you manipulate the independent variable “reason for disease contraction.” In one condition you describe the victim as having contracted AIDS through homosexual contact. In the other condition you describe the person as having contracted AIDS from a contaminated blood supply while receiving a blood transfusion. You ask subjects to rate on a 1 to 10 scale the extent to which each person deserves medical treatment. You include as a second factor the following subject variable: the educational level of the respondent (did not complete high school, completed high school but not college, graduated from college).

a. Diagram (using a box diagram/matrix) the experimental design. (1 pt)

b. Identify the independent variables and their levels and indicate for each independent variable 1) whether it is manipulated or selected (non-manipulated) and 2) whether it is within- or between-subjects. (2.5 pts)

c. Identify the dependent variable. (.5 pt)

d. Graph the results that you expect to find and explain what you have graphed in terms of main and interaction effects. Note: There are 3 effects (2 main effects and 1 interaction) that you need to discuss. (4.5 pts)

2. The following design matrix shows cell means for an experiment involving two variables: Factor A and Factor B.

Factor A

a1 a2 a3

b1 10 15 40

Factor B

b2 20 25 30

Would you suggest that a main effect is present for Factor A? For Factor B? Is there an interaction between A and B? What specific numbers (you’ll need to calculate them) would you use to back up each of your three answers? Note: Assume that cell sizes, i.e., number of subjects in each condition, are equal. Also, assume that any difference between means is significant. However, keep in mind that main effects and interactions can be confirmed only through appropriate inferential statistics. (4.5 pts)

3. The following design matrix shows three calculated cell means for a two variable (Factor A and Factor B) design.

Factor A

a1 a2

b1 20 30

Factor B

b2 40 ?

a. Assume that the statistical analysis of the experiment showed a significant main effect of Factor A, no main effect of Factor B, and an interaction between A and B. What must the value of the missing cell mean be for this pattern of results to be obtained? Again, assume that any difference between means is significant. (2 pts)

b. Assume that the analysis of the means had revealed two significant main effects but no interaction. What must be the value of the missing cell mean for this pattern of results to be obtained? (2 pts)

4. Access the following CITI (Collaborative Institutional Training Initiative) website:

https://www.citiprogram.org

Complete the ethics tutorial (“Basic Course”) for Social and Behavioral Researchers & Students; it takes about 2 hours to complete. Then print out and turn in your “Completion Report.” Note: You will need to register as a New User first. (7 pts)