what does it mean when there is a horizontal line over a variable in a
statistical equation? see link:
http://office.microsoft.com/assistance/hfws.aspx?AssetID=HP052090961033&CTT=98.

The horizontal line above a variable is (in a statistical context)
used to indicate the average value of the variable.

"Now that we have this nice notation, let's use it to come up with
expressions for the sample mean, which we'll write as the letter 'x'
with a bar over it, and the standard deviation, s. The mean is easy.
It's the sum of the observations (which we've already done) divided by
the sample size"
from:
( http://www.tufts.edu/~gdallal/summary.htm )

_
X = SUM(Xi) / n
with
Xi = single values of X
n = amount of values for X

Iīve simplified the formual given in the above reference as we canīt
use graphics here.


I hope this helps to solve your problem.


till-ga

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