STAT 8010 Lecture Notes - Lecture 3: Interquartile Range, Box Plot, Unimodality
1 Sep 2016
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Document Summary
It is important to always create a key to go along with stem-and-leaf plots. Stem-and-leaf plots: symmetric = mirror image, the same on the left and right sides, uniform = all bars are approximately the same height, skewed right = longer right tail, skewed left = longer left tail. Spread = the amount of variability in a data set. Outliers = data points that are inconsistent with the rest of the data points. Parameter = any calculation that is based on the population data (a census) Statistic = any calculation that is based on the sample data. In a histogram, the peaks are called modes: one peak = unimodal, two peaks = bimodal, often bimodal data is a result of the inclusion of two groups in one histogram. Histograms are only really useful for addressing spread when comparing two histograms to each other. Sample median = the middle value in an ordered sample. Variance and standard deviation are not robust.
