How to plot a normal distribution - Bell curve

[Sebastien]

I have the daily volatility of Brent crude over the last year. So my column
A is the date, and column B is the volatility. I have around 300 datapoints.

I want to fit these datapoints in a normal distribution plot to see the
"Bell curve" shape.
How can I do this?

 

[Sebastien]

This is good theory, but I would like to have a formula in Excel. Is there a
function or a n easy way ot generate the normal distribution chart?

 

[Joel]

1) Get the mean using the average function of your data
2) Get the standard deviation of your data using stdev function
3) Add new column with normal() function
a) column B will be the first parameter X.
b) Average will be the mean
c) Standard Dev is from 2 above
d) cumulative will be FALSE.

4) Plot columns b and c as a scatter plot.

NORMDIST(x,mean,standard_dev,cumulative)

 

[Sebastien]

Thanks, that works fine for the Bell shape curve, the X axis shows my
volatility data. The only problem is that the Y axis in the chart is the
Normdist() function number (so always less than zero). I would like to have
the number of occurence "N" of the data. Is this easy to get?

 

[Mike Middleton]

Sebastien -

You mention "300 datapoints" and "Bell curve."

Usually, you first determine a frequency distribution and histogram (column
chart of the frequency distribution, with value ranges on the horizontal
axis and frequency "count" on the vertical axis).

Second, you might want to see if the frequency distribution is approximately
like a normal distribution.

For the frequecy distribution and histogram, you can use the Histogram tool
of Excel's Analysis ToolPak (check Excel's built-in Help). Or, you could use
my free Better Histogram add-in, available from the Histogram page at
www.treeplan.com.

It's also possible to add a normal curve to a histogram. An example workbook
(but without step-by-step instructions) is available in the Excel Examples
section of the home page at www.MikeMiddleton.com.

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