Prediction–variance relation in a state-space fish stock assessment model

Abstract The state-space assessment model (SAM) is extended by allowing a functional relationship between observation variance and the corresponding prediction. An estimated predicted value for each individual allows to assign smaller (or larger) larger log-observations. This relation different from usual assumption of constant log-observations within age groups. prediction–variance link implemented compared official assessments North East Arctic cod haddock. For both these stocks, found give significant improvement.