Creating a graphical bell curve form Excel data...

[Guest]

Hello.

Using the example from the http://tushar-mehta.com/... site, I have a mean
of 1.55 and a standard deviation of .6176. Now when I plot the data as per
the example on the site, the y-axis starte at 0 whereas the chart extends
into negative terriroty making for a Bell Curve that look's a little strange
to me. So, I guess my questions are (1) is this normal,meaning that does the
chart properly show the standard deviation, (2) is there another suggested
approach to use to get a normal bell curve to appear, starting from 0 on the
x axis? My column A plot points start at -2.51 and edn at 2.49 in increments
of .1. I did this just to get column B to show a 0.

Thank you.

Mark

 

[Guest]

Hi,

Yes, for your mean and standard deviation values, the bell curve WILL extend
to negative x values. A span of mean plus or minus 3 standard deviations
approximately covers close to 99.9% probability. So for your mean and
standard deviation, that would correspond to an x-axis range of 1.55 + or -
3x0.6176. So the bell curve will extend from slightly less than -0.3 to
slightly above 3.4.

Regards,
B. R. Ramachandran