line graph

line graph: a series of points connected by lines

also known as a line chart: A line graph is a type of chart used to visualize the value of something over time.

Defintion Line graphs compare two variables. Each variable is plotted along an axis . A line graph has a vertical axis and a horizontal axis. So, for example, if you wanted to graph the height of a ball after you have thrown it, you could put time along the horizontal, or x-axis, and height along the vertical, or y-axis.

When to use a line graph:

Distributions of data over time: trends
Continuous data

Line graphs are generally not our best option for:

Close comparisons of data
Representing individual values

How to Create a Line Graph

  • Create a table.
  • Draw the x- and y-axes on the page. ...
  • Label each axis.
  • If time is one of the factors, it should go along the horizontal (x) axis.
  • The other numeric values measured should be placed along the vertical (y) axis.
  • Each axis should be labeled with the name of the numeric system as well as the measurements being used.
  • Divide each axis evenly into applicable increments.
  • Add data. Data points are plotted and connected by a line in a "dot-to-dot" fashion.
  • Data for a line graph is usually contained in a two-column table corresponding to the x- and y-axes.
  • Create a key.
  • Title graph.

MORE: Most line graphs only deal with positive number values, so these axes typically intersect near the bottom of the y-axis and the left end of the x-axis. The point at which the axes intersect is always (0, 0). Each axis is labeled with a data type. For example, the x-axis could be days, weeks, quarters, or years, while the y-axis shows revenue in dollars.

Data points are plotted and connected by a line in a "dot-to-dot" fashion.

The x-axis is also called the independent axis because its values do not depend on anything. For example, time is always placed on the x-axis since it continues to move forward regardless of anything else. The y-axis is also called the dependent axis because its values depend on those of the x-axis: at this time, the company had this much money.

More than one line may be plotted in the same axis as a form of comparison.

the good

title/key/x and y axis labeled
line graph

color as key indicator creates clear comparison between data sets
line graph showing comparison

the not so good

no clear trend or change, title or key
line graph with not title or key