plugin-Chapter 21a Students

# plugin-Chapter 21a Students - What is a Confidence Interval...

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CHAPTER 21A What is a Confidence Interval?

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RECALL Parameter fixed, unknown number that describes the population Statistic known value calculated from a sample a statistic is used to estimate a parameter Sampling Variability different samples from the same population may yield different values of the sample statistic estimates from samples will be closer to the true values in the population if the samples are larger
RECALL Example : The amount by which the proportion obtained from the sample ( ° ) will differ from the true population proportion ( p ) rarely exceeds the margin of error . Sampling Distribution tells what values a statistic takes and how often it takes those values in repeated sampling. Example: sample proportions ( ° ’s) from repeated sampling would have a normal distribution with a certain mean and standard deviation.

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SAMPLING DISTRIBUTION OF P-HAT Let ° denote the proportion of successes obtained in a random sample of n = 400 items selected from a population where the population proportion is p = 0.4.
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## This note was uploaded on 08/05/2011 for the course STA 200 taught by Professor Wierdhobbitguy during the Summer '08 term at Kentucky.

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plugin-Chapter 21a Students - What is a Confidence Interval...

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