caa a22 4500 397551231 CHVBK 20180308164750.0 cr unu---uuuuu 161202e199606 xx s 000 0 eng 10.1006/jmsc.1996.0079 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0079 Stefánsson Gunnar Marine Research Institute, P.O. Box 1390, Skúlagata 4, 121 Reykjavík, Iceland Analysis of groundfish survey abundance data: combining the GLM and delta approaches [Elektronische Daten] [Gunnar Stefánsson] This paper describes a method for the analysis of groundfish survey data by incorporating zero and non-zero values into a single model. This is done by using a model which modifies the delta-distribution approach to fit into the GLM framework and uses maximum likelihood to estimate parameters. No prior assumptions of homogeneity are used for the structure of the zero or non-zero values. The method is primarily applicable to fixed-station designs, although extensions to other designs are possible. The maximum likelihood estimation reduces to fitting a GLM to 0/1 values and another GLM to the positive abundance values. The new model is tested on Icelandic groundfish survey data. It is seen that the model can be used for evaluating the effect of different factors on catch rates as well as estimating abundance indices. Results from different models are compared on the basis of tuned VPA runs. © 1996 International council for the Exploration of the Sea Articles nationallicence generalized linear models nationallicence marine surveys nationallicence ICES Journal of Marine Science Oxford University Press 53/3(1996-06), 577-588 1054-3139 53:3<577 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0079 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0079 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Stefánsson Gunnar Marine Research Institute, P.O. Box 1390, Skúlagata 4, 121 Reykjavík, Iceland NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/3(1996-06), 577-588 1054-3139 53:3<577 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford