Dr. André Punt1
1US SAFS
October 13, 2015 9:00 (PST): FSH 203
Some Insights into Data Weighting in Integrated Stock Assessments
The results of fishery stock assessments based on the integrated analysis paradigm can be sensitive to the values for the factors used to weight each of the data types included in the objective function minimized to obtain the estimates of parameters. These assessments generally include index data, length-composition information and conditional age-at-length data, and algorithms have been developed to select weighting factors for each of these data types. This paper introduces methods for weighting conditional age-at-length data that extend an approach developed by Francis (2011) to weight age- and length-composition data. Simulation based on single-zone and two-zone operating models are used to compare five tuning algorithms that are constructed as combinations of methods to weight each of these data types. The single-zone operating models allow evaluation of the algorithms in terms of the ability to provide unbiased estimates of management-related quantities and the correct data weights in the absence of model mis-specification while the two-zone operating models allow the impacts of model mis-specification on the performance of tuning algorithms to be explored.