CCT226H5 Lecture Notes - Lecture 5: Standard Deviation, Random Variable, Weighted Arithmetic Mean
27 Sep 2018
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Indicates how large the standard deviation is inn relation to the mean (s/xline x 100): standard deviation divided by the mean (multiply by 100 for percentage) (recall: square root of variance is standard deviation) Just shows the lowest percentage estimate: does not make assumption about the distribution, need to use other rules for more data. Incorrectly included into data set: correctly recorded value that belongs in set, though sometimes might still be purposefully excluded to avoid its misleading representation on data set. In earlier example most extreme (largest and smallest) z-scores are -1. 20 and 2. 27: using +3/-3 criterion for outlier, there are no outliers in this set. Weighted mean: when the mean is computed by giving each data value a weight that reflects its importance, it is referred to as a weighted mean, weighted average, ex. Descriptive statistics: relationships among variables: crosstabulations, scatter diagrams, measures of association between 2 variables.
