Chapter 5 for Stats

# Chapter 5 for Stats - Chapter 5 Measures of Variability...

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Chapter 5 Measures of Variability

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Variability measure of spread, or dispersion, of a set of data Four main measures: Range Interquartile range Variance Standard deviation
Range – high score minus low score Interquartile range (IQR) – IQR = Q 3 – Q 1 useful when interested in middle scores only considers 50% of scores does not take into account all information

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Variance involves determining the distance of each raw score from the mean of the data deviation (d) sum of all deviations around the mean must be __________ A. 0 B. 2 C. -1 D. 10
Example calculations of deviations from the mean Fish size (X) d d ABS 58 -17.2 17.2 60 -15.2 15.2 71 -4.2 4.2 81 5.8 5.8 86 10.8 10.8 95 19.8 19.8 ΣX = 451 Σ d = 0 Σ d ABS = 73 Mean X = 75.2

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A service station repaired 18, 12, 20, 11, 14, and 17 flat tires on ten consecutive days. What are Σ d and Σ d ABS ? A. 72 and 0
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## This note was uploaded on 05/25/2008 for the course IPHY 2800 taught by Professor Decker,mik during the Fall '08 term at Colorado.

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Chapter 5 for Stats - Chapter 5 Measures of Variability...

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