André Punt¹, Ian Taylor², and Owen Hamel^2
1School of Aquatic and Fishery Science
²Northwest Fisheries Science Center
February 11, 2015 14:00 (PST)

Data reweighting (and the Francis Method)

Weighting of data is fundamental to modern stock assessment science based on ‘integrated’ methods of assessment. There is considerable experience with weighting index data, and the methods for doing this have largely stabilized. This is not however the case for composition data even though it is clear that inappropriate weighting of composition data can lead to markedly biased estimates. This Think Tank focuses on two methods for calculating the effective sample size for composition data (McAllister-Ianelli and Francis) as well as how estimates of effective sample size should be combined over years. A key focus for the Think Tank and future work is how to apply the “Francis method” to conditional age-at-length data. With luck, approaches for addressing this question will arise during the Think Tank.