Histograms, cumulative frequency and box plots
Pages
Frequency density
Why unequal class widths force frequency onto area via frequency density.
Drawing a histogram
Frequency densities for every class, with bar areas carrying the frequencies.
Interpreting a histogram
Frequencies from bar areas, and why the tallest bar need not hold the most data.
Completing a histogram and its table
Using one known bar to fix the density scale, then finishing the table and bars.
Cumulative frequency graphs
Running totals plotted at upper class boundaries, joined by an S-shaped curve.
Reading a cumulative frequency graph
Estimating the median and quartiles from the curve, and counts above a point.
Drawing a box plot
The five values a box plot shows, from a list or a cumulative frequency graph.
Reading a box plot
The median, quartiles and range from a plot whose box holds the middle half.
Practice
Frequency density
Why unequal class widths force frequency onto area via frequency density.
PracticeDrawing a histogram
Frequency densities for every class, with bar areas carrying the frequencies.
PracticeInterpreting a histogram
Frequencies from bar areas, and why the tallest bar need not hold the most data.
PracticeCumulative frequency graphs
Running totals plotted at upper class boundaries, joined by an S-shaped curve.
PracticeReading a cumulative frequency graph
Estimating the median and quartiles from the curve, and counts above a point.
PracticeDrawing a box plot
The five values a box plot shows, from a list or a cumulative frequency graph.
PracticeHistograms review
Frequency density and unequal class widths.
PracticeCumulative frequency review
Curves, medians, quartiles and box plots.