summary statistics notes

summary statistics notes - variance(formula given in class...

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Notes on summary statistics Presume that we have a set of values (numbers) that have been collected. The set represents some information we’d like to consolidate (summarize). Summary statistics attempt to do that. They tend to be categorized into at least three kinds of measures. - Measures of the “center” of the data (what is a “typical” observation)? - mean (average value) - median (middle value of the data after ordering, or average of two middle values if there are an even number of observations) - mode (most frequently occurring value) - Measures of spread (or dispersion or variability) - range (largest value minus smallest value)
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Unformatted text preview: - variance (formula given in class, as well as page 123 of textbook)- standard deviation (square root of variance)- Measures of position – to be discussed- percentiles- quartiles MUST be able to compute mean and standard deviation quickly on a scientific calculator, and understand common interpretations of them. Also need to know and understand which measures tend to be used when as well as how extreme values (“outliers”) affect them. Interpretations: Empirical rule x ± 2 (sd), etc. (substitute something besides 2) Chebyshev’s rule x ± 2 (sd), etc. Summary statistics...
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This note was uploaded on 02/01/2012 for the course STAT 490 taught by Professor Boyer during the Spring '11 term at Kansas State University.

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