PSYC 3000 Lecture Notes - Lecture 5: Exit Poll, Sampling Distribution, Statistic
17 Nov 2016
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7. 1 how sample proportions vary around the population proportion . The total number of voters in a population is typically millions, and an exit poll only samples a minuscule portion of them. This section introduces a type of probability distribution called the sampling distribution that helps us determine how close to the population parameter a same statistic is likely to fall. Using exit polls, polling organizations predict winners after learning how a small number of people voted, often only a few thousand out of possibly millions of voters. For example: in 2010 gubernatorial election in california, after sampling 3889 randomly selected voters, 53. 1% said they voted for brown, 42. 4% for whitman and 4. 5% for other/no answer. At the time of the exit poll, the percentage of the entire voting population (nearly 9. 5 million people) that voted for brown was unknown.
