1. A researcher was interested in determining whether incentives affect the response rate in surveys. A simple random sample of 50 adult residents of a large city was selected. All were mailed a survey and promised a check upon returning a completed survey. Ten were promised a check for $1.00, 10 were promised a check for $5.00, 10 were promised a check for $10.00, 10 were promised a check for $25.00, and 10 were promised a check for $50.00. The amount ($1.00, $5.00, $10.00, $25.00, or $50.00) promised to each person was determined by randomization. For each person who was sent one of the surveys, the researcher recorded whether or not a completed survey was returned.
We wish to fit a logistic regression model
where p is the binomial probability of returning a completed survey, and log is the natural logarithm. The fitted logistic regression model is
If we increase the amount promised by $1.00, the odds that the survey will be returned increases by how many times?
A. -0.8894 + 0.0516(amount promised)
B. 0.0516
C. 1.0530
2. Could mud-wrestling be the cause of a rash contracted by University of Washington students in the spring of 1992? Two physicians at the University of Washington health center wondered this when one male and six female students complained of rashes after participating in a mud-wrestling event. Questionnaires were sent to students in the residence halls that participated in the event. The questionnaire asked about the appearance of a rash and about attendance at the mud-wrestling event. The results, by gender, are summarized in the following table.
Male Female
Developed rash 12 12
No rash 38 8
The odds that a male who attended the event developed a rash is
A. 0.24.
B. 0.32.
C. 1.00.