Dot plot maker

Type or paste the numbers, separated by commas, spaces or new lines. The sample is how many pets 15 children have. Each value gets one dot above its place on the number line, and repeats stack upwards.

Pick crosses if your class draws them that way, which many US worksheets do. Mark the median, or the mean and median both, to see where the middle falls. Anything typed in the label box goes under the line, such as Number of pets.

Download saves the plot as an SVG. It's a drawing rather than a photo of one, so it stays sharp however far you enlarge it, and it opens in any browser as well as in Word or Google Docs. The working below the plot counts each value, so you can check a plot drawn by hand. It takes up to 200 values.

Every dot is one value. That's the whole idea. The height of a stack is how often that value came up, so the tallest stack is the mode. You can see the spread at a glance, and gaps and outliers stand out on their own.

Look at the shape. A plot that piles up on the left with a long tail to the right is skewed right. Two separate humps often mean two groups mixed together, like the heights of a class of 7-year-olds and their parents.

A dot plot keeps every value, which a histogram doesn't. That makes it best for small sets of whole numbers. Past a few dozen distinct values the stacks thin out to single dots, and a box plot shows more.

They're the same chart. US schools call it a line plot in the early grades, often drawn with crosses. The Common Core has second graders measure lengths and show them on a line plot marked in whole numbers (2.MD.D.9). By grade 6 the name is dot plot, listed alongside histograms and box plots (6.SP.B.4).

Statisticians use the name for two charts. Confusingly, they're not alike. Leland Wilkinson described the stacked kind in The American Statistician in 1999. William Cleveland's dot plot, from his 1993 book Visualizing Data, is something else. It puts one dot per category on a scale, as an alternative to a bar chart.