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math 1530
3-3: measures of variation
Question | Answer |
---|---|
Range | The difference between the Maximum data value and the minimum data value |
Round off rule of measures fo variation | carry one more decimal place than is present in the original set of data, found only the final answer |
Standard deviation | measure of cariation of values about the mean, denoted by lowercase s |
Variance | a measure of variation equal to the square of the standard deviation |
Range Rule of thumb | based on the principle that for many data sets, the vast majority of a sample values lie within two standard deciations of the mean |
Properties of standard deviation | -measures the variation among data values, -valuses close together have a small standard deviation, but values with much mroe variation have a larger standard deviation, -has same units of measurement as original data |
Properties of standard deviation cont. | a vaule is unusual if it differs from the mean by more than 2 standard deciations |
Empirical Rule | 68-95-99.7 rule, for data sets haveing a sistribution that is approxiimately bell shaped |
Chebyshev's Theorem | Proportion (or fraction) of any set of data lying within K standard deviations of the mean is always at least 1-1/k^2, where K is any positive number greater than 1. |