Statistical Chart Makers

Which chart for which job

One numeric variable, and you want its shape: a histogram for more than about thirty values, a stem-and-leaf plot for fewer — it keeps the original digits — and a box plot when you need to compare several groups at once.

Two numeric variables: a scatter plot, every time. It is the only chart that shows the relationship rather than a summary of it.

Categories to compare: a bar chart, sorted by size unless the categories have a natural order. A pie chart works only for parts of one whole, and only with a handful of slices.

A sequence over time: a line graph. The line implies the space between points means something, which is true for time and false for categories.

A matrix of values: a heatmap, on a single-hue scale so that darker always means larger.

Three rules these tools enforce

Bars start at zero. Truncating the axis of a bar chart is the most common way a chart misleads, and it is not offered here.

No dual axes. Two measures on two y-scales let you place the crossing point anywhere you like. Two charts, or one indexed to a common base, say the same thing honestly.

Colour is never the only channel. Every chart ships a data table, direct labels where they fit, and a colour order chosen to stay distinguishable for the most common forms of colour-vision deficiency.

Downloading

Every chart draws to a canvas, so you can right-click and save it, or use the download button below the figure for a PNG. Nothing is uploaded to produce it — the drawing happens in your browser.