Biostat Test Notes

# Biostat Test Notes - Population size means Sample is a...

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Population size means Sample is a subset of y-values means sample size possible subsets Therefore, the probability of a given sample is If you have one value fixed and you ask what the probability is that you are in the sample you calculate For is which is for All Whenever everyone has an equal chance of being in the sample, you have an SRS. Second order inclusion probabilities: (Doing second order is what gives you standard errors) Total: Sum of all values in the population; Total: ; Mean: Second order inclusion probability is the probability that appears with Classical Infinite population sampling- fixed samples with random values that are random vs. finite population sampling- fixed values with random samples Every type of sampling has to give everyone a chance to be in the sample When estimating a population total, you can use the Horvitz-Thompson Estimator: SRS: HTE is always unbiased is the probability that i is in the sample is the probability that I and j are in the sample To get the standard error, you need a , so you can get Stratified mean: with as the sample mean is the finite population correction (the error) (fpc) meaning the closer n is to N, the less of an error there is HTE is good because it lets us think about statistical abnormality criteria and we need information about normality Frame: a list of identifiers that allow us to draw the sample ; PPSWR= probability proportional to size with replacement PPSWOR= probability proportional to size without replacement Find probabilities of possible samples being in it There is a different probability of getting AD and DA can occur as AB or BA so Therefore, For a sample of then the HTE of , meaning can be both quantitative and qualitative but it needs to be binary for qualitative and is an estimate of and is an estimate of The Harvis Thompson estimate of is is the weight of SRS: is the inflation factor for estimator: 1. Theoretically calculate the variance of what you are estimating 2. Find empirical estimate 3. Take square root:

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## This note was uploaded on 01/28/2012 for the course STATISTICS 3010 taught by Professor Ooz during the Spring '11 term at Cornell.

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Biostat Test Notes - Population size means Sample is a...

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