normal distribution and/or standard deviation

[colettey29]

Is there an easy way that I can create a chart for a normal distribution
and/or input data so that a chart includes one standard deviation above and
below a specific number? (I have the exact numbers of the mean and what one
standard deviation is... just trying to figure out how to set this up in
excel to easily create a chart.) thanks in advance!!

 

[Mike Middleton]

colettey29 -

If you want a chart of the normal density function (bell-shaped curve) with
vertical lines to indicate the one-standard-deviation range, one way is to
enter x values in a column on the left with NORMDIST values in a column on
the right. Select the data in both columns and create an XY (Scatter) chart.
Then enter data (XY pairs) for the two lines, each of which can be defined
using just two XY data points, and add each new data series to the chart
using the Source Data tab. If you need more detailed instructions, specify
which version of Excel you are using.

- Mike Middleton
http://www.DecisionToolworks.com
Decision Analysis Add-ins for Excel

 

[mforrest]

"Then enter data (XY pairs) for the two lines, each of which can be defined
using just two XY data points, and add each new data series to the chart
using the Source Data tab. If you need more detailed instructions, specify
which version of Excel you are using." - I am using Excel 2007 and I don't
understand how to do what you have described above. Could you please explain
further.

 

[Mike Middleton]

mforrest -

For example, if you want a chart of the normal density function for mean =
100 and stdev = 10, enter the values 70, 71, ...,129, 130 in column A, e.g.,
in A2:A62. In cell B2, enter =NORMDIST(A2,100,10,FALSE), and copy from B2
down to B62. Select A2:B62, and in Excel 2007, choose Insert | Scatter |
Scatter With Smooth Lines.

For a vertical line at 90, enter (for example) 90 in D2, 0 in E2, 90 in D3,
and 0.025 in E3. Click on the chart to select it, and choose Chart Tools |
Design | Select Data. In the Select Data Source dialog box, click Add. In
the Edit Series dialog box, leave the Series Name blank, select or enter the
range D23 for Series X Values and the range E2:E3 for the Series Y Values.

Similarly, enter 110, 0, 110, and 0.025 in other cells, and add another
series.

Select the horizontal axis, and format the scale for min = 70 and max = 130.
And much other formatting may be needed.

- Mike Middleton
http://www.DecisionToolworks.com
Decision Analysis Add-ins for Excel

 

[mforrest]

Thank you very much. This was very helpful.

 

[Treasur2]

Perfect. Straight forward. this is what I was looking for.