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

Olav Nikolai Breivik*, Anders Nielsen, Casper W. Berg

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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The state-space assessment model (SAM) is extended by allowing a functional relationship between observation variance and the corresponding prediction. An estimated relationship between observation variance and predicted value for each individual observation allows the model to assign smaller (or larger) variance to predicted larger log-observations. This relation is different from the usual assumption of constant variance of log-observations within age groups. The prediction–variance link is implemented and compared to the usual constant variance assumption for the official assessments of North East Arctic cod and haddock. For both of these stocks, the prediction–variance link is found to give a significant improvement.
Original languageEnglish
Article numberfsab205
JournalICES Journal of Marine Science
Issue number10
Pages (from-to)3650-3657
Number of pages8
Publication statusPublished - 2021


  • Mean-variance relationship
  • Observation variance
  • SAM


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