CRIM 220 Lecture Notes - Lecture 8: Probability Theory, Convenience Sampling, Sampling Bias
8 Aug 2015
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Document Summary
What is sampling: the process of selecting observations. 2 reasons to sample: often not possible to study entire pop, often not necessary to study entire pop, allows researchers to use info from a small subset of obsv and then generalize to the rest of the pop. 2 types of sample: probability, can specify for ea element of pop the prob that it will be included in the sample, nonprobability, no way to estimate the probe a element has of being incl. in the sample. Random selection: key is random selection, ea. True population average (formula on p. 211: avrg of infinite # of sample statistic = Sample stats wil cluster around value of pop parameter. We can estimate how closely they will cluster (using the stnd error: that enable us to express the accuracy of our sample stats in terms of a level of confidence.
