Question

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. 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) Condition Rating 1 1.6667 1 3 1 1.6667 1 2.3333 1 4 1 2.3333 1 2 1 2.6667 1 2.6667 1 2.3333 1 3.3333 1 2.3333 1 2.3333 1 2.6667 1 3 1 2.6667 1 3 1 2 1 2.3333 1 2.6667 1 3 1 3.3333 1 3 1 2.6667 1 2.3333 2 2.6667 2 2 2 2 2 1.3333 2 1.6667 2 2.3333 2 2.6667 2 2 2 1.6667 2 1.3333 2 2.3333 2 2 2 2.3333 2 2.3333 2 2.3333 2 2.3333 2 1.6667 2 3.6667 2 2.3333 2 2.6667 2 2 2 2.3333 2 2.3333 2 3.3333 Exercises 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?

Answer 1

1)

Independent variable: Treatment condition: Charismatic condition/Punitive condition

2)

The stem and leaf plot is obtained R.

R code:

Charismatic<-c(1.667,3.000,1.667,2.333,4.000,2.333,2.000,2.667,2.667,2.333,2.333,2.333,2.333,2.667,3.000,2.667,3.000,2.000,2.333,2.667,3.000,3.333,3.000,2.667,2.333)

Punitive<-c(2.667,2.000,2.000,1.333,1.667,2.333,2.667,2.000,1.667,1.333,2.333,2.000,2.333,2.333,2.333,2.333,1.667,3.667,2.333,2.667,2.000,2.333,2.333,3.333)

stem(Charismatic, scale =1)

stem(Punitive, scale =1)

R output:

For Charismatic

For Punitive

3)

R Code

sd (Charismatic, na.rm = FALSE)

sd (Punitive, na.rm = FALSE)

R Output

4)

The box plots are obtained in R,

R Code:

boxplot(Charismatic, Punitive, names = c("Charismatic", "Punitive"))

Punitive condition have some outliers