Dear Simon, Many thanks for pointing me to the GAMM! For clarification, Bird_abundance are breeding densities ( e.g. 1.25 BP/ha, 2.20 BP/ha,...) and count is just the actual survey(e.g. first_survey,...). The dataset looks like Bird_abundance Study_area YEAR COUNT X1 X2 X3 X4 0.15 area_1 2004 first_survey 1.26 area_1 2004 second_survey 2.47 area_1 2005 third_survey 0.00 area_1 2005 fourth_survey 0.23 area_1 2006 fifht_survey 2.64 area_1 2006 sixth_survey 4.14 area_2 2004 first_survey 5.00 area_2 2004 second_survey 6.80 area_2 2005 third_survey 0.15 area_2 2005 fourth_survey 0.25 area_2 2006 fifht_survey 2.36 area_2 2006 sixth_survey 2.59 area_3 2004 first_survey 6.31 area_3 2004 second_survey 0.15 area_3 2005 third_survey 2.85 area_3 2005 fourth_survey 2.48 area_3 2006 fifht_survey 1.23 area_3 2006 sixth_survey
Am I correct in assuming the following is a valid syntax for this repeated measures design?: model <-gamm(Bird_abundance ~ YEAR + s(X1)+ s(X2)+ s(X3)+ s(X4),random=list(count=~1,park=~1)) best wishes and thanks again, Diederik Diederik Strubbe Evolutionary Ecology Group Department of Biology, University of Antwerp Universiteitsplein 1 B-2610 Antwerp, Belgium http://webhost.ua.ac.be/deco tel : 32 3 820 23 85 -----Original Message----- From: Strubbe Diederik Sent: Wed 28-1-2009 18:09 To: r-help@R-project.org Subject: Repeated measures design for GAM? - corrected question... Dear all, I have a question on the use of GAM with repeated measures. My dataset is as follows: - a number of study areas where bird abundance has been determined. Counts have been performed in 3 consecutive years and there were 2 counts per year (i.e. in total 6 counts). - a number of environmental predictors that do not change over year Xi). When using a GLM, a repeated measures design would like: (for example) lme(Bird_abundance = study_area + count +year+ X1 + X2 + X3,random = ~count|study_area). However, I have found no analogue design for a GAM. For now, I have averaged my bird abundances but I wondered whether a more subtle and elegant strategy exists...? Many thanks, Diederik Diederik Strubbe Evolutionary Ecology Group Department of Biology, University of Antwerp Universiteitsplein 1 B-2610 Antwerp, Belgium http://webhost.ua.ac.be/deco tel : 32 3 820 23 85 [[alternative HTML version deleted]]
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