Langolis and Roggman (1990) took photographs of numerous human faces. From these

ID: 2947631 • Letter: L

Question

Langolis and Roggman (1990) took photographs of numerous human faces. From these photographs, they used a computer to average the faces together to create 5 prototypical faces. These prototypes differed in the number of faces averaged together to make each prototype (Faces used to create the prototypes: 2, 4, 8, 16, and 32). Next, participants were randomly placed into 5 groups, with each group tasked with rating the attractiveness of one of the faces. Ratings for attractiveness were whole numbers that ranged from 1 (not attractive) to 5 (very attractive). The results are below. Langolis and Roggman wanted to determine if the number of faces used to make a prototype face influences the attractiveness of the prototype face. Please evaluate their question using an ? = .05.

Data on rated attractiveness:

Group 1

Group 2

Group 3

Group 4

Group 5

2.201

1.893

2.906

3.233

3.200

2.411

3.102

2.118

3.505

3.253

2.407

2.355

3.226

3.192

3.357

2.403

3.644

2.811

3.209

3.169

2.826

2.767

2.857

2.860

3.291

3.380

2.109

3.422

3.111

3.290

a. State symbolically and in words what your H1 and Ho are.

b. What are your df (you should identify 3 df’s)? What is your critical F?

c. What is the value of your observed F?

d. Based on the above information, would you reject H0, or fail to reject it? Why? What would your conclusion be?

e. Calculate Cohen’s d (an estimate of effect size) for the difference between groups 1 and 5.