ANOVA stratum

An ANOVA stratum is an orthogonal response subspace representing one level of experimental variation, such as between blocks or within blocks. In a covariance model scalar on each such subspace, its eigenvalue supplies the common variance scale for its projected coordinates. Treatment and residual sums of squares in ANOVA must be compared within appropriate strata.

The within-block ANOVA stratum contains response vectors whose coordinates sum to zero separately in every block. For $b$ blocks of size $k$ its dimension is $b(k-1)$. A shared additive block effect cancels in every vector in this subspace.