Assume that students are distributed RANDOMLY in a college hallway. Which research design is used here?

What follows is a true story.

Three researchers, Lindsay Levine, Thomas Bluni, and Sidney Hochman, were interested how people responded to non-verbal communication in the form of personal artifacts, specifically, how people were dressed. In their literature review they found that people were generally more likely to cooperate with or help people who were nicely dressed.

They decided to extend this research to the question of charitable behavior. Their proposition was that better dressed solicitors for charitable causes would get more donations than poorly dressed solicitors.

To test this, they recruited three female high school students as confederates. The confederates each assembled two sets of clothes: for “Preppy” attire they wore neat, pressed, well-coordinated and tailored clothing, and new shoes; for “Messy” attire they wore unpressed, uncoordinated clothing, tee shirts, loose sweaters, and worn, dirty sneakers.

Each confederate was assigned to a different floor of a large college building. They wore one of the outfits as determined by a flip of a coin for each confederate. They each held an official American Cancer Society coin collection can, and were instructed to ask every third student passing them by, “Will you contribute?” After thirty requests the confederates changed into their other suit, returned to their floor, and asked thirty more students “Will you contribute?”

The confederates were told they were helping raise money for the American Cancer Society. They were not told the proposition.

Observers watched the confederates from a discreet location. They recorded the success or failure of each request. A request was considered successful if a) the solicited student donated or b) they reached into their pocket for money, whether they actually donated or not.

This protocol led the researchers to the hypothesis that preppie-dressed confederates would be more likely to get a donation or attempted donation than messily-dressed confederates.

Okay, ready?

1. Assume that students are distributed RANDOMLY in a college hallway. Which research design is used here? (5 points)

2. Why were the confederates not told about the proposition? (2 points)

3. Does the manipulation of attire possess face validity? Why or why not? (2 points)

4. What was conducted as a pretest? (2 points)

Now for the fun part. Sorry, I can’t help myself: mua ha ha ha ha.

Here are the Observed outcomes. The numbers in this table refer to the number of students.


                                                Preppie            Hippie             Marginal

                        Yes                       50                    18                    68


                        No                        40                    72                   112

Marginal                                       90                    90

You will note I have calculated the marginals for you. The experimental protocol has also simplified your life in a mathematical way you will see if you know what you are doing. 🙂

5. What is the Expected value for each cell? (10 points)

6. What is the chi-squared f or the table? You are required to do this by hand. Include an image – I don’t care how you get it – of your work. No image, no credit. (20 points)

7. How many Degrees of Freedom in this test? (2 points)

8. What is the Critical chi-squared for this test assuming alpha = .10? Yes, I said .10. (2 points)

9. Are the results statistically significant or non-significant? (2 points)

10. Is the hypothesis supported or falsified? (3 points)

There are a total of 50 points available for the homework. I promise I will not curve the scores down. Partial credit is available for questions 1, 5, and 6 ONLY.