Dr Bellus Wants to Study How People's Perception of Attractiveness

Essay

Dr. Bellus wants to study how people's perception of attractiveness is affected by the gender of the subjects, and the facial expression of the object. Each participant views six headshots (in random order) of the same person, who demonstrates different facial expressions (joy, surprise, fear, anger, sadness, and disgust) in each picture. The participants are then asked to rate the attractiveness level of each picture. The rating is the dependent variable. Below is the selected output of a two-factor split plot ANOVA.

Test of Between-Subjects Effects
Test of Within-Subjects Effects

$\begin{array}{ccccc}\hline \text { Source } & \text { Type III SS } & d f & \text { MS } & F \\\hline \text { A (between-subjects factor) } & 226.81 & 1 & 226.81 & 3.04 \\\mathrm{~S} \text { (subject) } & 2084.61 & 28 & 74.45 & \\\hline\end{array}$

a. Identify the between-subjects factor and within-subjects factor.
$\begin{array}{ccccc}\hline \text { Source } & \text { Type III SS } & d f & \text { MS } & F \\\hline \text { B (within-subjects factor) } & 18802.53 & 5 & 3760.506 & 38.07 \\\text { A*B } & 324.22 & 5 & 64.84 & 0.66 \\\text { B*S }^{*} & 13829.70 & 140 & 98.78 & \\\hline\end{array}$

b. Are the effects significant ( $\alpha$ = .05)? What do these results tell us about people's perception of attractiveness?
c. Is MCP necessary? If so, on which effect(s) should we conduct MCP?