CRIM 220 Lecture Notes - Lecture 7: Simple Random Sample, Convenience Sampling, Nonprobability Sampling
17 Mar 2016
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What is sampling: what process of selecing observaions, 2 reasons to sample: Oten not possible to study enire populaion (someimes too big) Oten not necessary to study enire populaion (generalize to pop you care about) Can specify for each element of populaion the probability that it will be included in the sample: nonprobability. No way to esimate the probability each element has of being included in the. Probability sampling sample: each member of populaion has a known and non-zero chance of being selected, can generalize to larger populaion, a useful sample contains same variaions that exist in populaion. The unit about which informaion is collected: populaion. A theoreically speciied grouping of sample elements: sampling frame. Ex. the key demographics, list of names, etc. How you"re going to access your sample elements: populaion parameter. The value for a variable in a populaion: sample staisics. Sampling frame = list of 30,000 student #s.
