Statistics & Data Science, Mathematics
High School (9–10)
High School (11–12)
Undergraduate
General
Statistics Basics › Spread of DataStatistics Basics › Tables and GraphsChapter 2Describing Distributions
Thirty students write down how long their journey to school takes.
- A list of thirty numbers says very little.
- A picture of the list says a lot: where most values sit, how far they spread, and whether a few lie far away.
- In this chapter you draw histograms and box plots, read the shape of a distribution, find outliers with a clear rule, and measure spread with the standard deviation.
- You also learn to compare a value with its group through a z-score.
- Small Python programs do the counting, so you can spend your time on what the numbers mean.
Part of Statistics & Data Science · Essentials (chapter 2)
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Histograms and the Shape of Data
Sort thirty journey times into bins and a shape appears: a hill, a long tail, perhaps two humps. Learn to draw a histogram, to choose the width of its bins, and to name the shape you see. Then find out why a long tail pulls the mean away from the median, and which of the two to report.
Five-Number Summaries and Box Plots
Five numbers can tell the story of a whole data set: the smallest value, the quartiles, the median and the largest value. Draw them as a box plot, use a clear rule to decide which values are outliers, and decide what to do with one. Then put two box plots side by side and compare two groups at a glance.