STAT 344 Chapter Notes - Chapter unit1: Simple Random Sample, Variance, Sampling Distribution
6 Feb 2018
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Unit #1: intro stat plus a bit more. In this unit, we tweaked and pushed the boundaries on some intro stat concepts. It immediately follows that every possible subset s of n population members has probability 1/(cid:16)n n(cid:17) of becoming the sample. Depending on what de nitions you saw in intro stat, you might have to tweak your thinking just slightly. In particular, if you were told that random sampling involves strict independence, so that your chance of being sampled doesn"t depend on what happens to others, you need to recognize that this isn"t quite true. In advance of any sampling, you have a n/n chance of being selected. But if your friend has been picked to be in the sample, then your chance of being picked is lowered slightly. Your friend is occupying one of the n spots in the sample, leaving only n 1 available spots. So your chance of inclusion is now (n 1)/(n 1).
