If the assumptions are violated , a possible solution is to use the Greenhouse & Geisser or the Huynh & Feldt adjustments to the degrees of freedom .
They can correct for issues that can arise should the sphericity of the covariance matrix assumption be violated .
If the assumptions are violated , a possible solution is to use the Greenhouse & Geisser or the Huynh & Feldt adjustments to the degrees of freedom because they can correct for issues that can arise should the sphericity of the covariance matrix assumption be violated .