Research conducted by: Annette
Towler and Robert Dipboye

Case study prepared by: Emily
Zitek

Overview

How powerful are rumors? Frequently, students ask friends and/or
look at instructor evaluations to decide if a class is worth taking.
Kelley (1950) found that instructor reputation has a profound impact
on actual teaching ratings, and Towler and Dipboye (1998) replicated
and extended this study.

Subjects were randomly assigned to one of two conditions. Before
viewing the lecture, students were given a summary of the instructors'
prior teaching evaluations. There were two conditions: Charismatic
instructor and Punitive instructor.

Then all subjects watched the same twenty-minute lecture given by
the exact same lecturer. Following the lecture,
subjects answered three questions about the leadership qualities
of the lecturer. A summary rating score was computed and used as
the variable "rating" here.

Questions to Answer Does
an instructor's prior reputation affect student ratings?

Design Issues The data presented
here are part of a larger study. See the references below to learn
more.

Descriptions of Variables

Variable

Description

Condition

this represents the content of the description that the students
were given about the professor (1 = charismatic, 2 = punitive)

Rating

how favorably the subjects rated the professor after hearing
the lecture (higher ratings are more favorable)

References

Kelley, H. H.(1950). The warm-cold variable
in first impression of persons. Journal of Personality,
18, 431-439.

Towler, A., & Dipboye, R. L. (1998).
The effect of instructor reputation and need for cognition
on student behavior (poster presented at American Psychological
Society conference, May 1998).

Plot stem and leaf displays of the ratings for each condition.

What is the standard deviation of the ratings in the charismatic-reputation
condition? What is the standard deviation of the ratings
in the punitive-reputation condition?

Plot side-by-side box plots for the ratings by condition.

In which of the two conditions are there outliers?

Conduct an independent-samples t-test to examine the
difference between the mean ratings of the charismatic-reputation
condition and the punitive-reputation condition. Is the
difference in mean ratings statistically significant? What
can you conclude?

Compute a confidence interval on the difference between
the means of the two conditions.