A Harvard psychologist recruited 75 female hotel maids to participate in a study. She randomly selected 41 and informed them (truthfully) that the work they do satisfies the Surgeon General’s recommendations for an active lifestyle, providing examples to show them that their work is good exercise. The other 34 maids were told nothing. Various characteristics of the maids, such as weight, body fat, body mass index, and blood pressure, were recorded at the start of the study and then again after four weeks. The researcher was interested in whether the information she provided would result in measurable physical changes. If there is a difference, it could challenge our understanding of the placebo effect (in which subjects who receive the null treatment are not informed) by showing that being informed about a treatment can make a difference.

What conclusion can you draw from the test in Exercise 10?
a) The maids lost weight, on average.
b) The mean BMI for the informed maids changed during the study.
c) The mean difference in BMI was not zero for the maids who were informed that their work qualifies as an active lifestyle.
d) The mean change in BMI was greater for the maids who were informed that their work qualifies as an active lifestyle than for those who were not informed.

e) Maids should concentrate on the exercise aspect of their jobs.

Data From Exercise 10

The researcher was concerned about whether each maid’s BMI  changed over the four-week study. Here are the results of a test  performed using technology:

Using the proper notation, how would you write the null hypothesis tested?

Transcribed Image Text:

Mean of Paired Differences 0.2068 t-Statistic = 3.853 w/72 df P = 0.0003 =