In: Statistics and Probability
A researcher wishes to estimate, with 90% confidence, the population proportion of adults who think Congress is doing a good or excellent job. Her estimate must be accurate within
22% of the true proportion.
(a) No preliminary estimate is available. Find the minimum sample size needed.
(b) Find the minimum sample size needed, using a prior study that found that 20%
of the respondents said they think Congress is doing a good or excellent job.
(c) Compare the results from parts (a) and (b).
A researcher wishes to estimate with 90% confidence, the population proportion of adults who think Congress is doing good or excellent job. Her estimate must be accurate within 22% of the true proportion.
That is margin of error of me=0.22
The minimum sample size needed: