Source of variation

MS

EMS

Factor A

MS_A

${\sigma }_e^2+bn{\sigma }_A^2$

Factor B

MS_B

${\sigma }_e^2+an{\sigma }_B^2$

A * B interaction

MS_A*B

${\sigma }_e^2+n{\sigma }_{AB}^2$

Error (Residual)

MS_error

${\sigma }_e^2$