# What are line graphs?

Mar 24, 2014

A line graph is a graph that uses points connected by straight lines. It shows how something changes in value as something else happens.

Scientists use graphs to help them visualize and understand the data collected from experiments. For example, you may measure the speed of an object at certain points in time.

Then you draw a line graph. You plot the points corresponding to time on the horizontal axis and speed on the other axis. Then you join consecutive points by straight-line segments and get a line graph like the red line below. The graph shows that that, overall, the speed increases with time. But it is not likely that the speed zigzags up and down and passes exactly through each of the data points. This is more likely caused by uncertainty in your measurements.

Often we include a “best-fit” line. This is the graph of a mathematical function whose points come as close as possible to the data points. Spreadsheets and graphing software do this for you. They give a graph like the blue line above. Note that the line does not have to go through any point.

Mar 24, 2014

A line graph is a graph that uses points connected by straight lines. It shows how something changes in value as something else happens.

Scientists use graphs to help them visualize and understand the data collected from experiments.

For example, you may measure the speed of an object at certain points in time.

Then you draw a line graph. You plot the points corresponding to time on the horizontal axis and speed on the other axis.

Then you join consecutive points by straight-line segments and get a line graph like the red line below. The graph shows that that, overall, the speed increases with time. But it is not likely that the speed zigzags up and down and passes exactly through each of the data points. This is more likely caused by uncertainty in your measurements.

Often we include a “best-fit” line. This is the graph of a mathematical function whose points come as close as possible to the data points. Spreadsheets and graphing software do this for you. They give a graph like the blue line above. Note that the line does not have to go through any point.