Psy 300 Exam 2 Review

Psy 300 Exam 2 Review - This fluctuation is the standard...

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Psy 300 Exam 2 Review Chapter 6 Probability: the probability of A = number of outcomes classified as A Total number of possible outcomes Ex. The probability of selecting the king of hearts from a card deck is 1/52 The probability of selecting an ace is 4/52 (King of Hearts or an ace would be considered the A) Random Sample: - every individual in a population has an equal chance of being selected - there must be a constant probability across selections - problem: there isn’t a constant probability! - solutions: two: 1) replacement; 2) assumption of infinite populations -stratified sampling - making efforts to create a representative sample by forcing certain proportions Chapter 7: Sampling Distributions standard error – how much error is in a sample sampling error – samples are typically not identical to the population standard error stuff x σ is the standard error of X (or standard deviation) We want the standard error to be small If our mean (x-bar) is 20 we guess it might fluctuate by 5
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Unformatted text preview: This fluctuation is the standard error If your sample is the entire population (sample = population) then your standard error = 0 Maximum standard error: if your sample number is 1, then standard error is equal to that of standard deviation so…. x = σ Sampling distribution stuff-collection of sample means for all possible random samples of a particular size (n) that are drawn, with replacement, from the population- this is NOT a distribution of scores, but a distribution of statistics- sample means tend to center on population mean- distribution is approximately normal (helps us later)- we can ask/answer questions about sample means (ex: p (sample mean > 7)? ) Central Limit Theorem-“ for any population with mean μ and standard deviation σ , the distribution of sample means for sample size n will have a mean of μ and standard deviation of n , and will approach a normal distribution as n approaches infinity.”...
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This note was uploaded on 04/02/2008 for the course PSY 300 taught by Professor Galen during the Fall '05 term at Grand Valley State.

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