AMS 102 Lecture Notes - Lecture 4: Standard Deviation, Negative Number
17 Oct 2016
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Document Summary
Coefficient of variation (cv) cv= s/ x sample (s) (when means are not the same) The range rule of thumb is that for many data sets, the vast majority of the sample values lie within two standard deviations from the mean: the sample values inside these boundaries are usual . The values greater or smaller than this minimum are unusual : for example, it is unusual to earn a bachelor"s degree in 12 years. It isn"t reasonable to expect someone to get that degree in 12 years. The time is a lot higher than the expected average. Minimum usual value = (mean) 2 x (standard deviation) = 6. 5 2 x (3. 5) = -1. 5 (negative number does not make sense) Maximum usual value = (mean) + 2 x (standard deviation) = 6. 5 + 2 x (3. 5) = 13. 5: therefore, it is usual for someone to take anywhere from 0 to 13. 5 years to get a bachelor"s degree based on this sample.
