Highest-ranked (ΔAICc<2) and other GLMMs for observer chick-aging accuracy accuracy (correct or incorrect estimation of chick age) in laboratory trials.

Fixed factors included tool use (“Tool”), experience (any previous experience with birds = experienced, [“Exp”]), chick age group (“Group”), and test date (“Date”). Tool use was retained in 89% of the top 18 ranked models: models ranked 17 and 18 were the only ones not to retain tool use as a factor. Model selection (reduction) began from the maximal model (not shown) that included all two-way and three-way interactions. Two models which did not include tool use as a predictor are shown for comparison. Number of parameters (k), and AICc weights are given.Highest-ranked (ΔAICc