|
A researcher is estimating the population proportion of U.S. adults ages 18 to 24 who have had an HIV test. The estimate must be accurate within 2% of the population proportion with 90% confidence. Find the minimum sample size needed when
(1) No preliminary estimate is available and
(2) A previous survey found that 31% of U.S. adults ages 18 to 24 have had an HIV test.
a. Identify , , zc, and E. If is unknown, use 0.5.
b. Use , , zc, and E to find the minimum sample size n.
c. Determine how many U.S. adults ages 18 to 24 should be included in the sample. |
| New search. (Also 1294 free access solutions) |