How to Create a Histogram Online
A histogram is a type of bar chart that represents a frequency distribution in statistical analysis. The height of each bar tells you how many times a certain item was observed in a particular category. For example, you might use a histogram to plot the heights of students, with categories for 4 to 5 feet tall, 5 to 6 feet tall and 7 to 8 feet tall. The height of the bar would represent the relative number of students with heights that fell into each category.
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Instructions
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Locate an online histogram tool, such as one by the National Council for the Teachers of Mathematics (NCTM), Shodor or Zweigmedia.
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Enter the data for the histogram in the appropriate box, following the site's instructions. For example, the NCTM histogram tool requires you to enter your data, one per line. For heights of students, you might enter:
5.2
5.1
5.4
5.3
5.7
5.1
5.6
5.8
6.0 -
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Enter the interval size. You'll want to play around with this to get a decent graph. For the height data above, you might have categories of "5.0 to 5.25," "5.25 to 5.5," 5.5 to 5.75," and "5.75 to 6.0." Some sites will choose the interval for you. For example, the Zweigmedia histogram calculates intervals based on your data.
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Enter a title for your histogram in the appropriate box, if requested.
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Press the "Update," "Results" or "Create" button. (This button will differ depending on what tool you use.)
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Tips & Warnings
A good histogram should have between four and 20 categories.
Play around with the frequencies and categories to achieve a visually effective graph. Unlike drawing a graph, where you must make precise decisions before putting pencil to paper, an online tool allows you to play around with the numbers to get a nice-looking histogram.
Don't overlap your categories. For example, if you have a height of 5.7, don't end your category with 5.7 and start another with 5.7. The program will either give you an error message, or possibly draw you an inaccurate graph.
