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Cards In This Set
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What does SRS stand for?
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Simple random sample
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Describe a population in terms of statistics
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The entire group of individuals in which we are interested, but can't usually access directly. Usually finite in size, but for research purposes we asume populations have infinite size. Infinite populations are imaginary, but most applied statistical techniques are based on the assumption of an infinite population. if the population is quite large and the sample is only a small proportion of the population, there would be no problem violating the infinite population size.
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Define a parameter in terms of statistics.
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A number describing a characteristic of the population. Usually unknown.
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Describe a sample in terms of statistics.
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The part of a population we actually examine and for which we do have data.
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Describe a statistic.
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A number describing a characteristic of a sample. We often use a statistic to estimate an unknown population paramater.
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What is bias?
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The design of a statistical study if biased if it systematically favors certain outcomes.
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What is a simple random sample (SRS)?
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Consists of n individuals from a population chosen in a way that every sest of individuals has an equal chance to be that sample actually selected.
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What is a systematic random sample?
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Also made of randoml selected individuals. each individual in the population has the same chance/probability of being in the sample. Your sample contains the individuals whos labels you find in the list.
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What is undercoverage?
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Occurs when parts of the population are left out in the process of choosing the sample.
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What is a sampling distribution of a statistic?
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The distribution of all possible values taken by the statistic when all possible samples of a fixed size (n) are taken from the population. THe sampling distribution of a statistic is the probability distribution of that statistic.
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What makes up the sampling distribution?
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When some sample means are above the population mean and some are below.
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What is at the center of the sampling distribution of the sample mean?
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The mean
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What does the standard deviation of a sampling distribution measure?
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How much the sample statistic mean varies from sample to sample.
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When a variable in a population is normally distributed, the sample mean for all possible samples of sizes is?
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Also normally distributed
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What is the central limit theorem?
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It allows us to use the normal probabiilty calculations to answer questions about sample means from many observations even the population distribution is not normal.
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