Bailey N-
What does statistic mean in sampling?
A measure used to describe a sample distribution
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What does parameter mean in sampling?
A measure used to describe a population distribution
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What is probability sampling?
A method that allows us to specify, for each case (observation) in the population, the probability of it's inclusion in the sample
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What are the 2 reasons for using probability sampling?
1. Ensures each case (observation) has the same probability of being selected
2. tries to make a sample as representative of the population as possible
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What is a simple random sample?
Designed to ensure that 1. every member of a pop. has an equal chance of being chosen 2. every combination of (N) members has an equal chance of being chosen
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What is a stratified random sample?
Method of sampling obtained by 1. Dividing the pop. into subgroups based on relevant variables 2. Selecting a simple random sample from each of those subgroups
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What is the benefit of using a stratified sample?
More realistic for large samples where every single person cannot realistically be accounted for
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What is the Central Limit Theorem?
Any large, properly drawn sample will resemble the population from which it was drawn.
The sample means for any pop. will be distributed roughly as a normal distribution around the pop. mean
This will be true no matter what the distribution of the underlying pop. looks like
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What are the 4 major points of the Central Limit Theorem in simple words?
1. If we have detailed info about a pop. we can make inferences about any properly drawn sample from that pop.
2. If we have detailed info about a properly drawn sample, we can make inferences about the pop. from which it was drawn
3. If we have data on a particular sample and pop. we can infer if that sample is likely to be drawn from that pop.
4. If we know underlying traits of two samples, we can infer if both samples are likely drawn from the same pop.
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What is the "sampling distribution of the mean"? What are its characteristics?
A distribution of sample means obtained by drawing from the pop. all possible samples of the same size
1. Is a theoretical probability
2. Normal distribution and symmetrical
3. It's mean is equal to the pop. mean
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What is the "standard error of the mean"? What are its characteristics?
The standard deviation of the sampling distribution of the mean that describes how much dispersion is in the sampling distribution of the mean
1. As the sample size gets larger, the standard error decreases
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What's something important about the sampling distribution of the mean as it relates to Z scores?
Because the sampling distribution is normal, we can use the Z table to find ares and probabilities, meaning we can use a known sample statistic to estimate an unknown pop. parameter
