How to find an interquartile range on a boxplot

Descriptive statistics, The basics 7 Comments

Finding an interquartile range on a boxplot is easy! (If you only have numbers, see How to  find an interquartile range from a set of numbers). This how-to will show you how to find an interquartile range in a couple of easy steps.

boxplot with whiskers

Let’s find the interquartile range for the above graph.

  • Step 1: Find Q1.Q1 is represented on a boxplot by the left hand edge of the “box”.
    finding q1 on the boxplot graph
    In the above graph, Q1 is approximately 2.5. (If you are interested, a better explanation of what Q1 is can be found in this article on finding the five number summary.)
  • Step 2: Find Q3.
    Q3 is represented on a boxplot by the right hand edge of the “box”.
    finding q3 on the boxplot
    Q3 is approximately 12 in this graph.
  • Step 3: Subtract the number you found in step 1 from the number you found in step 3.
    This will give you the interquartile range. 12 – 2.5 = 9.5.

Related posts:

  1. How to find an interquartile range in statistics
  2. How to Find Q1, Q3 and the Interquartile Range on the TI-89 calculator
  3. How to Find the TI 83 Interquartile Range
  4. How to read a boxplot and find the five number summary including Q1 and Q3
  5. How to Find a Five Number Summary and Create a BoxPlot on the TI-89 Graphing Calculator
Feel like Cheating at Statistics? This is the Statistics Handbook that your professor doesn't want you to see. So easy, it's Practically Cheating. Find out more »
Need more help? Ask on our free forums »

You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

7 Responses to “How to find an interquartile range on a boxplot”

  1. How to find an interquartile range in statistics « How to Do Everything Statistics said:

    Aug 22, 09 at 8:40 am

    [...] An interquartile range–the different between the biggest and smallest values in the middle fifty percent of data–can be a tricky concept to grasp at first. However, this article breaks it down into a couple of easy steps, so you’ll have the answer in no time! (If you have a boxplot, see this article to find the interquartile range). [...]

  2. Christine Mao said:

    Sep 12, 09 at 7:07 pm

    This article was simple to comphrehend. The diagram and the steps explain everything you would need to know. I was able to understand more of the interquartile range on a boxplot. The book helped, but the article was more helpful.

  3. Lisa Barcomb said:

    Oct 25, 09 at 6:25 pm

    I understood this article it was easy because of the diagram, its nice when you have the diagrams to look at and see what you are doing. But the interquartile range is alittle difficult by plotting it on the boxplot.

  4. Vanessa DuBarry said:

    Dec 14, 09 at 9:43 pm

    Very easy to learn this. Thanks for this blog!, its just way easier than the book explains it.

  5. crystal lydick said:

    May 04, 10 at 10:18 am

    Our book does not seem to explain innterequartile range as easily to me as our practically cheating book has. I do not understand our book as I do the practically cheating book.

  6. SeaTab said:

    Apr 11, 11 at 6:40 pm

    Thank you great site!

  7. Statistics How To» Blog Archive » How to find an interquartile range on a boxplot « Gregory Reese Research said:

    Sep 03, 11 at 1:51 pm

    [...] Statistics How To» Blog Archive » How to find an interquartile range on a boxplot. Advertisement LD_AddCustomAttr("AdOpt", "0"); LD_AddCustomAttr("Origin", "other"); [...]

Leave a Reply