How to make a Line Plot

How to Make a Number Line Plot


Latest update to this document: 25 February 2003


A line plot is a graph that shows frequency of data along a number line. It is best to use a line plot when comparing fewer then 25 numbers. It is a quick, simple way to organize data.


Data can be collected from a number of sources. The Internet, world almanacs, and person observation are all good sources. REMEMBER: Internet data is not always right, beware. Also, collected data must be controlled. That means the data must be collected under the same rules for each set. Example: If collecting data for the number of red M&M's per bag you should use all plain, or all peanut unless you state that the data collected is from a mixed group.


Once data is collected it is then time to make a line plot.

1. Determine the scale to be used. If the data is best described in 100's have the scale increase by hundreds, if all the data can fit on a scale 0-10 then make it 0-10.

2. Next draw a horizontal line across the paper.

3. Break the line into EQUAL parts that will hold your scale.

4. List the data. Place an X over the correct number for each of the datum collected. If a number is repeated then place the X above the other.

See below for sample chart.


Once you have constructed the plot it is then time to analyze the data.


1. OUTLIERS-data values that are substantially larger or smaller then the other values. When possible, try to find an explanation for any outliers you may find. If this was a graph representing the height of everyone in the class this outliers is most likely the teacher. Although this is not a number line plot, it gives a visual description of an outlier. The value near the top right is spaced away from the rest f the data making it an outlier.

2.GAPS-large spaces between points. In the example above the space between the data and the outlier is considered a gap. In the example below a gap occurs between 10 and 13.

3.CLUSTERS-isolated groups of points. These are places on the number line where data is concentrated. On this number line a large cluster appears from 0-4.

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