PDF download Download Article PDF download Download Article

Line graphs and bar graphs are both visual ways of representing two or more data sets and their interrelation. In other words, graphs are pictures that show you how one thing changes in relation to another. Learning to read graphs properly is a matter of interpreting which pieces of information go together.

  1. Most graphs will have a clearly labeled x-element, spaced along the graph's horizontal axis, and a clearly labeled y-element, spaced along the graph's vertical axis. [1]
    • The graph's title should also tell you exactly what it's about.
  2. This applies to both line graphs and bar graphs. [2]
    • For example, if you're looking at a graph that shows how many salmon returned to a given stream over the period of a few months last year, each increment along the graph's y-axis might represent hundreds, thousands or tens of thousands of salmon returning; you won't know which scale numbers apply until you check the graph.
    Advertisement
  3. [3]
    • For example, you might want to know how many salmon returned to the stream in question in August of last year. So you'd read across the graph's horizontal axis until you find "August."
    • Time elements, such as days, weeks, months or years, are almost always listed along the horizontal ("x") axis. Quantity measurements are almost always listed along the vertical ("y") axis.
  4. Then read straight across to the left until you hit the graph's labeled y-axis. [4] Whatever quantity that line intersects with is the measurement for salmon return in August.
    • So if you read up to the dot, line or top of the bar for salmon in August then read across to the left and hit "10,000," you know 10,000 salmon returned in August. If you hit a point between any two labeled graph increments, you have to estimate based on where you land between the 2 increments. For example, if you hit a point halfway between 10,000 and 15,000, you can safely estimate that the correct number is about 12,500.
  5. Advertisement

Community Q&A

Search
Add New Question
  • Question
    How do I graph 1920 population is 65,000; 1924 population is 100,000; 1925 population is 60,000?
    Donagan
    Top Answerer
    Let the x-axis be one set of numbers (say, the years), and let the y-axis be the other set of numbers (say, the populations). Plot the points corresponding to each pair of numbers (a given year and its population).
  • Question
    What is the trend when both variables increase?
    Donagan
    Top Answerer
    The trend is represented by a line moving up from left to right.
  • Question
    What is a coefficient?
    Community Answer
    A coefficient is a numerical or constant quantity placed before and multiplying the variable in an algebraic expression.
See more answers
Ask a Question
      Advertisement

      Video

      Tips

      • Line graphs give you 1 piece of explicit information that bar graphs don't. The steepness of the line connecting each data point on the graph (that is, each dot) indicates the rate of change. A steeply descending line, for example, would show that salmon returns dropped abruptly from 1 month to the next. But a slowly ascending line represents a gradual increase. [5]
      • If the graph correlates more than 2 elements, the extra data sets are usually assigned to the x-, or horizontal axis. Often, the additional data sets are graphed in another color to avoid confusion. So if you want to compare the salmon returns over the same months for more than 1 year at a time, you could graph each year's return on the same graph, but in a different color.
      Submit a Tip
      All tip submissions are carefully reviewed before being published
      Name
      Please provide your name and last initial
      Thanks for submitting a tip for review!
      Advertisement

      About This Article

      Thanks to all authors for creating a page that has been read 198,427 times.

      Reader Success Stories

      • Chiazodo Okonkwo

        Sep 25, 2017

        "The article has enhanced my ability to read line graphs."
      Share your story

      Did this article help you?

      Advertisement