Confidence interval for the difference in proportions

Question

Discussion:

Vacation occupancy rates were expected to be up during March 2008 in Myrtle Beach, SC. Data in the file Occupancy will allow you to replicate the findings presented in the newspaper. The data show units rented and not rented for a random sample of vacation properties during the first week of March 2007 and 2008.

1) Estimate the proportion of units rented during the first week of March 2007 and the first week of March 2008.

2) Provide a 95% confidence interval for the difference in proportions.

3) On the basis of your findings, does it appear March rental rates for 2008 will be up from those a year earlier?

Unit Rented?
March, 2007	March, 2008
Yes	No
No	Yes
Yes	Yes
No	No
No	Yes
Yes	No
No	No
No	Yes
No	Yes
Yes	Yes
No	No
Yes	No
No	Yes
No	Yes
No	Yes
No	Yes
No	No
No	Yes
No	Yes
No	Yes
No	Yes
No	No
Yes	Yes
Yes	No
Yes	Yes
Yes	No
No	Yes
Yes	No
No	No
No	No
No	Yes
Yes	Yes
No	No
Yes	Yes
No	No
Yes	No
No	Yes
Yes	Yes
Yes	No
No	No
No	Yes
Yes	Yes
No	No
No	Yes
Yes	No
Yes	No
No	Yes
No	Yes
No	Yes
No	Yes
No	No
No	No
Yes	No
No	No
No	Yes
No	No
No	No
No	No
Yes	No
No	Yes
Yes	No
No	Yes
No	Yes
Yes	No
No	No
No	No
No	No
Yes	No
No	Yes
No	No
Yes	No
Yes	No
Yes	No
No	No
No	Yes
No	Yes
Yes	Yes
No	No
No	No
No	Yes
No	Yes
No	Yes
Yes	No
No	No
Yes	Yes
No	No
Yes	Yes
No	No
Yes	No
No	Yes
No	Yes
No	Yes
Yes	Yes
No	Yes
No	Yes
Yes	Yes
No	Yes
No	Yes
No	No
No	No
Yes	Yes
No	No
Yes	Yes
Yes	No
Yes	No
No	No
No	No
Yes	Yes
No	Yes
Yes	No
Yes	Yes
Yes	No
No	No
Yes	Yes
No	No
Yes	No
No	No
Yes	No
Yes	No
No	No
No	No
No	No
No	No
No	Yes
No	Yes
No	No
No	Yes
No	No
Yes	No
Yes	No
Yes	Yes
No	No
No	Yes
No	Yes
Yes	No
No	Yes
No	No
Yes	No
Yes	No
No	No
Yes	Yes
Yes	Yes
No	Yes
Yes	No
No	Yes
Yes	Yes
No	Yes
Yes	No
Yes	No
No	No
No
No
Yes
No
No
No
No
No
No
No
No
No
Yes
Yes
No
No
No
Yes
No
No
No
No
No
No
No
Yes
Yes
No
No
Yes
No
No
Yes
No
Yes
No
No
Yes
Yes
No
No
No
No
No
Yes
Yes
No
No
No
No