How do we interpret a data matrix, X which does not have 1s as the first column? Does it refer to No Intercept Form?
Could it also be interpreted as the mean deviated form? I understand that for mean deviation form, (X′X)−1 matrix has order k−1∗k−1, but I cannot seem to derive the mean deviated form of (X′y) which has order k−1∗1. Please help.