PSYCH 2220 Lecture Notes - Lecture 5: Coin Flipping, Mutual Exclusivity, Random Assignment
21 Jun 2017
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Document Summary
A sample is a subset of a population. The sample is observable; the population may not be. We want to infer characteristics about the population by observing and describing the sample. To make valid inference about the population, the sample must be representative of the population, this is referred to as generalizability or external validity. Sampling from the population such that every member of the population has an equal change of being included in the sample. With a large enough sample size and an effective random selection procedure, your sample is likely to be representative of the population. Also known as probability sampling: ex: to obtain a random sample, you could draw numbers out of a hat, use a random number generator, etc. We can repeat studies, using samples with different characteristics. Replication can help us generalize our results: scientific progress is accomplished by an accumulation of evidence (collected with appropriate methods)
