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A new method to compute standard-weight equations that reduces length-related bias

January 1, 2005

We propose a new method for developing standard-weight (Ws) equations for use in the computation of relative weight (Wr) because the regression line-percentile (RLP) method often leads to length-related biases in Ws equations. We studied the structural properties of W s equations developed by the RLP method through simulations, identified reasons for biases, and compared Ws equations computed by the RLP method and the new method. The new method is similar to the RLP method but is based on means of measured weights rather than on means of weights predicted from regression models. The new method also models curvilinear W s relationships not accounted for by the RLP method. For some length-classes in some species, the relative weights computed from Ws equations developed by the new method were more than 20 Wr units different from those using Ws equations developed by the RLP method. We recommend assessment of published Ws equations developed by the RLP method for length-related bias and use of the new method for computing new Ws equations when bias is identified. ?? Copyright by the American Fisheries Society 2005.

Citation Information

Publication Year 2005
Title A new method to compute standard-weight equations that reduces length-related bias
DOI 10.1577/M04-196.1
Authors K.G. Gerow, R. C. Anderson-Sprecher, W.A. Hubert
Publication Type Article
Publication Subtype Journal Article
Series Title North American Journal of Fisheries Management
Series Number
Index ID 70027633
Record Source USGS Publications Warehouse
USGS Organization