Data analysis in Excel

[Tarita]

I am trying to analyze some data on Excel ( I do not have
a statistical software at hand)
What I need to know is, how can I test for normality in a
data set in excel.
The data analysis allows me to do a descriptive statistics
but I cannot figure whether the data is normal or non-
normal.
Does any one know how to go about doing this?

 

[Jerry W. Lewis]

Excel has no built-in tests for that purpose.

The usual quantitative tests, such as Shapiro-Wilk would require that
you insert tabled values
http://www.itl.nist.gov/div898/handbook/prc/section2/prc213.htm
or use a commercial Add-In such as
http://www.analyse-it.com/shapiro-wilk-normality-test_y.htm

You could do a rough and ready chi-square test, by dividing the real
line into n intervals, each having an expected value under normality of
at least 5 observations with your sample size. Then sum
(Observed-Expected)^2/Expected and compare to CHIINV(alpha,n-1) where
alpha is suitably small (say 0.05)

Qualitatively, you could plot the data as a histogram and observe
whether it looks roughly bell-shaped.

A more discriminating qualitative approach would be to do a normal
probability plot. Mike Middleton has a downloadable paper on this at
http://www.usfca.edu/~middleton/data.htm

There is an open source statistical package that is freely available
http://www.r-project.org

Jerry