STAT-2300 Lecture Notes - Lecture 6: Standard Deviation
3 Mar 2017
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Document Summary
Measures of position describe the relative position of a particular data value within the entire set of data. Z-score: this is the distance that a data value is from the mean in terms of standard deviations. For example, a z-score of 1. 24 means that the data value selected is 1. 24 standard deviations away from the mean, but a z-score of -2. 5 means a data value is 2. 5 standard deviations below the (cid:373)ea(cid:374) (cid:271)e(cid:272)ause it"s (cid:374)egative. If the data value is larger than the mean, the z-score is positive. If the data value is smaller than the mean, the z-score is negative. If the data value equals the mean, the z-score equals zero. The z-score is often found using this equation: The z-score is very good at determining outliers because the same percentage rules apply to z-scores that apply to the values of a normal distribution.
