Oliveira, AmilcarOliveira, TeresaMexia, João Tiago2012-03-022012-03-022008Oliveira, Amílcar; Oliveira, Teresa; Mexia, João Tiago - Analysis of residuals and adjustment in JRA. "Biometrical Letters". ISSN 1896-3811. Vol. 45, Nº 1 (2008), p. 45-541896-3811http://hdl.handle.net/10400.2/2058Joint Regression Analysis (JRA) is based in linear regression applied to yields, adjusting one linear regression per cultivar. The environmental indexes in JRA correspond to a non observable regressor which measures the productivity of the blocks in the field trials. Usually zig-zag algorithm is used in the adjustment. In this algorithm, minimizations for the regression coefficients alternate with those for the environmental indexes. The algorithm has performed very nicely but a general proof of convergence to the absolute minimum of the sum of squares of residues is still lucking. We now present a model for the residues that may be used to validate the adjustments carried out by the zig-zag algorithm.engJoint Regression AnalysisZiz-zag algorithmResidualsjournal article