The paper introduces conditions of difference-based minimax estimates of the regression parameters β in a semiparametric model. The ordinary least squares estimator βdiff based on higher order differences of the observations, and the minimax linear estimator of β are considered at the same time. Furthermore, the difference-based ridge regression estimator βdiff （k） that used in the presence of multicollinearity in a semiparametric model, and the conditions of βdiff ...
