Statistical Sciences 1024A/B Chapter Notes - Chapter 2: Interquartile Range, Quartile, Standard Deviation
18 Jan 2017
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Document Summary
Measuring centre: the mean = most common measure of centre. If distribution is exactly symmetric then mean & median are the same. Skewed distribution = mean is farther out than median. Quartiles = numerical description of distribution requires both measure of centre & measure of spread. To calculate = arrange in increasing order & locate median m. 1st quartile (q1) = median of observations left of median in list. 3rd quartile (q3) = median of observations right of median in list. 5 number summary = consists of smallest observation, 1st quartile, median, 3rd quartile & largest observation. Divides distribution into quarters leads to new way to display data (boxplot) Boxplot = central box spans the quartiles q1 & q3. A line in the box marks median m. Lines extend from box out to smallest & larger observations. Spotting suspected outliers: observed mins & max don"t describe spread of majority of data.
