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Table 9 Model selection for absolute growth using a backwards step-wise procedure.

From: The influence of gene-environment interactions on GHR and IGF-1 expression and their association with growth in brook charr, Salvelinus fontinalis (Mitchill)

  Absolute growth
Model Log likelihood Test P
Growth ~Env + Sex + EBV·Env + EBV·Sex +Env·Sex +EBV·Env·Sex (1) -107.460   
   ~Env + Sex + EBV·Env + EBV·Sex +Env·Sex (2) -108.443 1 vs. 2 0.169
   ~Env + Sex + EBV·Env + EBV·Sex (3) -108.499 2 vs. 3 0.737
   ~Env + Sex + EBV·Env (4) -108.607 3 vs. 4 0.643
   ~Env + Sex (5) -112.465 4 vs. 5 0.021
  1. Progressively simpler models are subsequently defined by removing terms from previous models beginning with interaction effects (e.g. 1 vs. 2). Nested models were tested evaluated using likelihood ratio tests to select the most parsimonious model. The reported p-values correspond to results of the likelihood ratio tests wherein a value greater than the nominal level of significance (α = 0.05) indicates that removal of the model term does not increase model deviance significantly. The final, parsimonious model that was selected is indicated in bold characters (Env = environment, EBV = EBV group).