Some remarks on the bias distribution analysis of discrete-time identification algorithms based on pseudo-linear regressions

In 1998, A. Karimi and I.D. Landau published in this journal an article entitled ''Comparison of the closed-loop identication methods in terms of bias distribution''. One of its main purposes was to provide a bias distribution analysis in the frequency domain of closed-loop output error identication algorithms that had been recently developed. The expressions provided in that paper are only valid for prediction error identification methods (PEM), not for pseudo-linear regression (PLR) ones, for which we give the correct frequency domain bias analysis, both in open-and closed-loop. Although PLR was initially (and is still) considered as an approximation of PEM, we show that it gives better results at high frequencies.