Hi Phenixbb, I have a data that indexes in P6122, also P61 and P31. Data analysis in phenix.xtriage says no twinning is suspected according to the L-test. However, after MR and twin RB refinement, the model improves from P6122 or P61 to P31 5% Rfacs and 0.5 the FOM. I thought the data might have RPS and twinning not detected with the L-test. So, i ran xtriage to compute the RvsR statistics using the obs_and_calc.mtz file and the results were: in P61 R_abs_twin observed data : 0.112 R_abs_twin calculated data : 0.047 in P31 R_abs_twin observed data : 0.117 R_abs_twin calculated data : 0.139 "misespecified crystal symmetry", according to Lebedev, Vagin, Murshudov et al 2006, Acta Cryst. D62,83-95. I would like to know a test that tells me the right symmetry. I appreciate your help. Thanks, Gabriela