Tonight, you have a worksheet on 2 sample t-intervals and 2-sample t-tests to complete. This is "new stuff." It is your job to figure out how to do these problems (you might need more space, so separate paper). The concepts are similar to our 2-proportion z-tests/intervals, so use those to help!
If you're stuck, look at the following to see some examples:
- Page 551-552 (2 sample t-interval, step by step)
- Page 553-554 (yellow box) shows how to use your calculator for this
- Page 556-558 (2 sample t-test, step by step)
- Page 558 (yellow box) shows how to use your calculator for this
- IGNORE EVERYTHING ABOUT A POOLED T-TEST IN THE TEXTBOOK
The paper “Ladies First?” A Field Study of
Discrimination in Coffee Shops (Applied
Economics [2008]) describes a study in which researchers observed wait
times in coffee shops in Boston. Both wait time and gender of the customer were
observed. The mean wait time for a sample of 145 male customers was 85.2
seconds; the mean wait time for a sample of 141 female customers was 113.7
seconds. The sample standard deviations (estimated from graphs in the paper)
were 50 seconds (for males) and 75 seconds (for females). Suppose that these
two samples are representative of the populations of both female and male
coffee shop customers.
1. Verify that the conditions for a 2-sample t-test/interval
are satisfied.
2. Estimate the difference in mean wait times for males and
females using 98% confidence.
3. Interpret this interval.
4. Is there convincing evidence that the mean wait time
differs for males and females? Test the relevant hypotheses using a
significance level of 0.05. (all 4 steps!)
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