Question

PSYC 2054: Worksheet 6

1. Research Study: We want to figure out what characteristics of boys are most attractive to high-school girls. High-school girls were randomly assigned three groups to hear about a guy with trendy clothes, a nice car, or a confident attitude. There were 9 girls in each group. They gave ratings on a scale from 1 to 10, with 1 being “not interested” and 10 being “very interested.”

Question: Is there a significant difference between the attractiveness ratings given by the three groups of girls?

What is the factor?

What are the levels of the factor?

Step 1: State Hypotheses

• Null:

• Research:

Step 2: Determine Comparison Distribution

• What is the distribution shape and degrees of freedom for the comparison distribution?

Step 3: Set the Criteria for a Decision

• Alpha = .05

• df_B =

df_W=

• Critical value:

• Is the rejection region placed in the upper or lower tail? How do you know?

Step 3: Compute the Test Statistic

Trendy Clothes	Nice Car	Confident Attitude
8	6	10
6	7	9
9	8	10
6	6	10
8	4	8
6	5	9
7	5	10
6	6	9
6	8	8

Step 5: Make a Decision

Reject/Fail to Reject the null?

            What does this mean (be sure to talk about significance)?

Answer 1

Factor : Characteristics of boys

Levels of the factor : Trendy clothes, a nice car, or a confident attitude

Hypothesis :

Null:  There is no significant difference between the attractiveness ratings given by the three groups of girls

Research: There is a significant difference between the attractiveness ratings given by the three groups of girls

Distribution : F distribution

Degrees of freedom for the comparison distribution : df₁ = 2 and df₂ = 24

Critical region :

F(2,24,0.95) = 0.051

F(2,24,0.05) = 3.403

If any value lies outside ( 0.051, 3.403) then we reject null hypothesis at 5% level of significance.

Rejection region is in upper tail because value of F distribution lies in the first quadrant and is always positive.

So, we would expect a test statistic value greater than 3.403 to reject null hypothesis.

Since, P-value = 0 < 0.05 (level of significance), we reject null hypothesis and conclude that There is a significant difference between the attractiveness ratings given by the three groups of girls at 5 % level of significance.