(a) A simple random sample of size n is defined to be A. a sample of size n chosen in such a way that every unit in the population has the same chance of being selected. B. a sample of size n chosen in such a way that every set of n units in the population has an equal chance to be the sample actually selected. C. a sample of size n chosen in such a way that every unit in the population has a known nonzero chance of being selected. D. All of the above. They are essentially identical definitions.
(b) In order to take a sample of 1200 people from a population, I first divide the population into men and women, and then take a simple random sample of 500 men and a separate simple random sample of 700 women. This is an example of a A. a simple random sample. B. a multistage sample. C. randomized comparative experiment. D. convenience sampling. E. stratified random sample.
(c) A small college has 500 male and 600 female undergraduates. A simple random sample of 50 of the male undergraduates is selected, and, separately, a simple random sample of 60 of the female undergraduates is selected. The two samples are combined to give an overall sample of 110 students. The overall sample is A. a simple random sample. B. a systematic sample. C. a stratified random sample. D. convenience sampling. E. a multistage sample.
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