STAB22H3 Chapter Notes - Chapter 6: Ibm 7070, Birth Weight, South Dakota Highway 10
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STAB22H3 Full Course Notes
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Chapter 6: the standard deviation as a ruler and the normal model (p. 121) 67 on exam a with mean 50 and sd 10. * if you multiply/divide all data values by a constant, all measures of centre and spread (mean & median) multiplied/divided by that constant. * if you add/subtract constant to all data values, measures of centre add/subtract that constant, but measures of spread unchanged while each value changes. 62 becomes (62-40)/12=1. 83 so the 62 is a (slightly) better performance, relative to the mean and sd. Standardized value (no unit) = z-score -> measure the distance of each data value from the mean in standard deviations above the mean. * positive z-score = x sd above mean; negative z-score= sd below mean. Data values below mean have (-) z-scores, so -1. 6 z-score= data value was 1. 6 sd below mean.
