Week 3 - STAT 218 Week#3 Chapters 5 and 6(partial Questions...

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STAT 218 Week #3 Chapters 5 and 6 (partial) Questions from HW or previous Class? CHAPTER 5 Skip continuity correction material – pg 172 OVERVIEW OF SAMPLES – IT IS NOT BLACK AND WHITE Sampling Distributions and Sampling Variability Samples are not unique Samples of size n are not unique Larger samples lead to BETTER estimates o More confidence in our estimates o Or less variability in the estimate o Or some intuitive sense that the more we sample the better it is Estimation We estimate unknown population parameters by sample statistics o Means for quantitative variables o Proportions for most categorical variables Biased vs Unbiased Sampling o Why is unbiased good and biased bad? Duh! Random Sampling Model o Framework for UNBIASED estimation of population parameters Review – PARAMETER VS STATISTICS STATISTIC – A characteristic of the sample PARAMETER - A characteristic of a population Both populations and samples have means, medians, standard deviations, etc. o Populations Have a distribution but the mean, standard deviation, and the key statistics DO NOT CHANGE o Samples Each Sample has a distribution It does change from sample to sample The collection of possible samples has a distribution because they are not unique Sample Statistics are used to estimate population parameters when population characteristics are not known 1
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Symbols that are used to denote parameters and statistics differ – refer to page 64 of textbook Pictorial representation of a population One possible sample Another… and another, and….an unlimited number of possibilities DIGRESSIOM – THEREARE THREE MAIN TYPES OF DATA WE WILL STUDY IN THIS CLASS / THREE DISTRIBUTIONS Three types of data Binominal Data – Categorical Data with two Outcomes – success/ failure Other Categorical Data – with three or more Outcomes
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Week 3 - STAT 218 Week#3 Chapters 5 and 6(partial Questions...

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