Business Intelligence Tools / Data Science & Analytics

Normal Distribution Curve on a Visualization

I received an interesting request from a user that deserves sharing.  The user requested a visualization showing the curve of a normal distribution of data points.  Now, just to be clear, a visualization that shows the distribution of data points is a histogram, which looks like this:

Histogram

histogram

The histogram might vary a little bit if you change the number of bins being used, but it always has the continuous value along the X-axis and the (Row Count) on the Y-Axis.  However, the user didn’t want to see the bars of the histogram, just a curve that represented the histogram, which would look like this:

Normal Distribution Curve

curve only

This type of visualization is simple and easy to create in Spotfire using the following steps.

Creating the Visualization

  1. Add a bar chart
  2. Configure the X-Axis with the continuous value and the Y-Axis with (Row Count)
  3. On the X-Axis, click the down arrow on the axis selector and make sure the “Auto-Bin” box is checked.
  4. If needed, right click on the axis selector and choose “Number of Bins” to set the desired number of bins.
  5. In the legend, click on the color circle and color the bars the same color as the background (probably white).
  6. Go to Properties > Lines & Curves > Add > Gaussian Curve fit

BAM!  Done!  The Gaussian Curve fit is the normal distribution and represents the histogram as a curve.  If you combine the curve and the histogram, it looks like this:

curve and histogram

 

In the end, Spotfire had the functionality to quickly and easily meet the user’s needs!

4 thoughts on “Normal Distribution Curve on a Visualization

  1. diy resin system Reply

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  2. jimbo_spotfire Reply

    That’s cool but I’d check the terminology – that curve is fitted but it’s not a normal distribution since it’s skewed – normal distributions take a bell shape because their tails are symmetrical.

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