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1 Comparing Mean, Median and Mode For negatively (left) skewed distributions Mean < Median < Mode Mode Median Mean
2 Skewed Right Mode Median Mean For positively skewed distributions Mean > Median > Mode
3 Symmetric Distribution Mean = Median = Mode For symmetric (not skewed) distributions Mean = Median = Mode
4 Variability Variability: No Variability:
5 Measures of Spread Different ways of computing the spread/variability of a dataset. 1.Range 2.Variance 3.Standard Deviation 4.Inter Quartile Range (IQR)
6 Range RANGE = Maximum – Minimum Easy to find Easy to interpret Depends only on the two extreme values Two datasets with same range could possibly have completely different variability. Not “Robust” ( influenced by “outliers”)
7 Variance VARIANCE tells us the squared distance between a typical observation and the mean of the data. Average squared distance between all the observations and the mean.