biunl brrefly A survey of Chicago, continued. The sample for the ey described in
ID: 3072915 • Letter: B
Question
biunl brrefly A survey of Chicago, continued. The sample for the ey described in Exercise 8.28 included 477 non nic black adults, 304 non-Hispanic whites, and 263 Hispanics. Results for the entire sample are considered be accurate within 4%, the margin of error for non- Hispanic blacks was ±5%, and for non-Hispanic whites to and Hispanics, the margin of error is 7%. (a) Why is the accuracy greater for non-Hispanic blacks than for non-Hispanic whites and Hispanics! (b) The poll details indicate For purposes of analysis, black and Hispanic respon- dents were oversampled. This involved (additional) random dialing in landline exchanges and cell phone areas with high proportions of minority residents.Explanation / Answer
Answer to part a)
The accuracy of a sample depends on the sample size. Larger the sample better the accuracy and smaller the sample lesser the accuracy. Since the Non-Hispanic blacks have been oversampled their accuracy is higher as compared to other groups
.
Answer to part b)
If the groups were not oversampled, their margin of error would have been larger. The only purpose of oversampling these groups is to give them equal presentation in the sample. There is a group that has larger proportion and there is another groups that has small proportion. In order to equate the two groups the larger group is sampled less, and the smaller group is oversampled.
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