Polarization measurement analysis - II. Best estimators of polarization fraction and angle L. Montier, S. Plaszczynski, F. Levrier, M. Tristram, D. Alina, I. Ristorcelli, J.-P. Bernard and V. Guillet A&A, 574 (2015) A136 Published online: 10 February 2015 DOI: 10.1051/0004-6361/201424451