Specify constant numeric values for each variance component in the
model, including the residual variance, in this field.
All power calculations are conditioned on these values. That is, they are assumed to be the true values of the variance components. Larger values correspond to more variability and less power.
You can determine appropriate values by running the ANOVA or
Mixed Model Analysis processes on pilot study data. Use a statistic such as the
mean or a
quantile from the empirical
distribution. To obtain these from the
_owa,
_amr, or
_mmr tables, click
Analyze > Distribution and select
variables beginning with
Variance_.