Consider the hypothetical example in Fleiss (1981, pp. 6 -7) in which a test is applied to a sample of 1000 people known to have a disease and to another sample of 1000 people known not to have the ...
Stratified sampling is used to select a sample that is representative of different groups. If the groups are of different sizes, the number of items selected from each group will be proportional to ...
Stratified sampling more effective than random sampling for detecting contaminants in infant formula
Producers of infant formula employ comprehensive food safety systems, including product testing to ensure those systems are working. A new study from the University of Illinois Urbana-Champaign finds ...
The authors advocate the use of the generalized variance of the sample means-the determinant of the variance-covariance matrix $D(\overline{y})$ of the means-as a ...
The method of simple random sampling (METHOD=SRS) selects units with equal probability and without replacement. Each possible sample of n different units out of N has the same probability of being ...
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