This dialog provides approximate power computations 
for a two-sample comparison of variances, assuming
independent random samples from normal populations,
and that the F ratio, F = (s1/s2)^2 is used as the
test statistic, where s1 and s2 are the sample SDs.

The sample sizes are inputted as n1 and n2.  The
"equal ns" checkbox forces them to be equal when
checked.

The variances to be compared are inputted via the
sliders for Variance 1 and Variance 2.  Use the
drop-down list to specify the alternative hypothesis
interest.  (The null hypothesis in all cases is that
Var1 = Var2.).  Use the alpha slider to set the
desired sugnificance level for the test.

The power slider displays the power of the test for
the current parameter settings.  This slider is not 
clickable.  To determine, say, the sample size for a
given power, vary n1 and/or n2 until the desired
power is achieved.
