A note on the extent of autocorrelation of residuals in the GLM analyses of penguin response variables in the feasibility study

One of the observations by the December 2014 IWS Panel on the penguin analyses presented in respect of the GLM analyses of penguin response variables was as follows:

“the observed residual patterns (some of the fits in MARAM/IWS/DEC14/Peng/B16 exhibit substantial serial correlation which needs to be reflected in the power calculations)”

This note examines this matter more systematically by estimating the autocorrelation in these residuals (Table 1) and also plotting the residuals themselves (Figure 1) and then the autocorrelation estimates (Figure 2) for the case of catches within a 10 nmi neighbourhood of the colony concerned, and either the combined sardine and anchovy catch (Robben and Dassen islands) or the sardine catch (St Croix and Bird islands).