Definition: A dot plot is a data display that places one dot above a number line for every data value, so repeated values stack in columns.
What is a dot plot?
A dot plot, or line plot, shows each data value as a dot over a number line. The height of a stack shows how often that value occurs.
How do you build one?
Mathbot counts the number of pets in 10 homes: 0, 1, 1, 2, 2, 2, 3, 3, 4, 7.
- Draw a number line from 0 to 7.
- Put 1 dot above 0, 2 above 1, 3 above 2, 2 above 3, 1 above 4, and 1 above 7.
What can you read from it?
The mode is the tallest stack, 2. The range is 7 – 0 = 7. The median is the average of the fifth and sixth values, 2 and 2, so it is 2. The dot at 7 stands apart from the rest, a possible outlier.
When does it work best?
It suits small data sets with whole-number values. For large sets, a histogram is easier to read.
What is a common mistake?
Spacing dots unevenly or skipping values with zero frequency on the axis. Every number in the scale should appear, even when it has no dots.