ENVS278 Chapter Notes - Chapter 5: Standard Deviation, Normal Distribution, Central Limit Theorem
4 Oct 2016
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Chapter 5 the standard deviation as a ruler and the normal model. To standardize a value, we subtract the mean and then divide this difference by the standard deviation. The values are called standardized values and are commonly denoted with the letter z we call them z-scores. Z-scores measure the distance of a value from the mean in standard deviations. A z-score of 0 says that a data value sits on the mean. A z-score of 2 says that a data value is two standard deviations above the mean. It does not matter which unit the original value was measured in, the units do not affect the z-score. Data values below the mean have negative z-scores; so a z-score of -1. 6 means that the data value was 1. 6 standard deviations below the mean. The further a data value is from the mean, the more unusual it is.
