The following PROC SURVEYSELECT statements select a probability sample of customers from the Customers data set according to the stratified sample design. title1 'Customer Satisfaction Survey'; title2 ...

Consider the example in the section "Stratified Sampling". The study population is a junior high school with a total of 4,000 students in grades 7, 8, and 9. Researchers want to know how much these ...

Ideally, when developing stratified medicines ... Some drug developers are addressing this by incorporating tissue sample collection into their clinical trials so that prospective–retrospective ...