Teacher Ratings

Research conducted by: Annette Towler and Robert Dipboye

Case study prepared by: Emily Zitek


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)


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).

  1. What is the independent variable in this study?
  2. Plot stem and leaf displays of the ratings for each condition.
  3. 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?
  4. Plot side-by-side box plots for the ratings by condition.
  5. In which of the two conditions are there outliers?
  6. 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?
  7. Compute a confidence interval on the difference between the means of the two conditions.