Eyewitnesses and mugshots. When an eyewitness to a crime

QUESTION:

Eyewitnesses and mugshots. When an eyewitness to a crime examines a set of mugshots at a police station, the photos are usually presented in groups (e.g., six mugshots at a time). Criminologists at Niagara University investigated whether mugshot group size has an effect on the selections made by eyewitnesses (Applied Psychology in Criminal Justice, April 2010). A sample of 90 college students was shown a video of a simulated theft. Shortly thereafter, each student was shown 180 mugshots and asked to select a photo that most closely resembled the thief. (Multiple photos could be selected.) The students were randomly assigned to view either 3, 6, or 12 mugshots at a time. Within each mugshot group size, the students were further randomly divided into three sets. In the first set, the researchers focused on the selections made in the first 60 photos shown; in the second set, the focus was on selections made in the middle 60 photos shown; and in the third set, selections made in the last 60 photos were recorded. The dependent variable of interest was the number of mugshot selections. Simulated data for this 3 X 3 factorial ANOVA, with mugshot group size at three levels (3, 6, or 12 photos) and photo set at three levels (first 60, middle 60, and last 60) are saved in the accompanying file. Fully analyze the data for the researchers. In particular, the researchers want to know if mugshot group size has an effect on the mean number of selections, and, if so, which group size leads to the most selections. Also, are there a higher number of selections made in the first 60, middle 60, or last 60 photos viewed?