Root mean square (RMS) error formula

L

Lea Olsen

Hello,

does anyone know what the formula for calculating root mean square (RMS)
error is? Can this be done in Excel?

Thanks,
 
H

Harlan Grove

Lea Olsen said:
does anyone know what the formula for calculating root mean square (RMS)
error is? Can this be done in Excel?
Click to expand...

RMS is just the (population) standard deviation of your residuals. If you
have actual data, Y, and fitted estimates of those data points, Z, your RMS
is given by the array formulas

=SQRT(DEVSQ(Y-Z)/COUNT(Y))

or

=STDEVP(Y-Z)

The former is less susceptible to truncation error.
 
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