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scottahindle
Community Trekker

How to fit a normal distribution of specified mean and standard deviation to a data set?

Suppose I create 100 values from a standard normal.

While my parameters are mean=0 and SD=1, the calculated statistics from the 100 data will not be fully equal to the parameter values.

If I use "Analyze" and "Distribution" I get a histogram of the 100 random data values and I can fit a normal distribution to these values ("Continuous fit" / "Normal"). The fit is based on the statistics of the data.

Rather than fitting a normal using the statistics as estimates of the parameters, can I fit a normal distribution using the mean and SD parameters I specify? (In this case zero and one.)

Would be great to have some advice on this.

Thanks!

 

 

 

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Accepted Solutions

Re: How to fit a normal distribution of specified mean and standard deviation to a data set?

You are not estimating the parameters, you are specifying them. I think you want to plot the PDF for the normal distribution over the histogram. A simple customization is sufficient. If you view the histogram in the default vertical orientation, then use the X Function( Normal Density( x, 0, 1 ), x ); If you rotated the orientation then use the Y Function( Normal Density( x, 0, 1 ), x ); Right-click in the histogram frame box and select Customize. Click the + button and add the JSL.

You get extra points if you figure out how to determine the curvecolor, style, and width...

Learn it once, use it forever!

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2 REPLIES 2

Re: How to fit a normal distribution of specified mean and standard deviation to a data set?

You are not estimating the parameters, you are specifying them. I think you want to plot the PDF for the normal distribution over the histogram. A simple customization is sufficient. If you view the histogram in the default vertical orientation, then use the X Function( Normal Density( x, 0, 1 ), x ); If you rotated the orientation then use the Y Function( Normal Density( x, 0, 1 ), x ); Right-click in the histogram frame box and select Customize. Click the + button and add the JSL.

You get extra points if you figure out how to determine the curvecolor, style, and width...

Learn it once, use it forever!

View solution in original post

scottahindle
Community Trekker

Re: How to fit a normal distribution of specified mean and standard deviation to a data set?

Thank you, Mark.
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