A priori determined comparison to be performed with a set of independent linear comparisons between levels of a factor in order to establish a significant main effect or interaction in an ANOVA. Doing so may result in a specific, but not an overall, difference. Carrying out planned comparisons can be based on theoretical and empirical considerations that support the differences being investigated. Alternatively, they are made instead of a series of post-hoc tests, thus enabling a more complex set of comparisons. .