Wiley, R. H.   2003.   Is there an ideal behavioural experiment?   Animal Behaviour 66:   585-588.


Much of the field of animal behaviour rests on experimental studies of the responses of animals to different classes of stimuli.   Playback experiments, which compare responses of animals to tape recordings of different sounds, are a prime example.   Consequently, the proper design of these experiments is central to the scientific study of animal behaviour.   Over a decade ago, a discussion of the design of behavioural experiments focused on the problems of pseudoreplication (Kroodsma 1989a, b, 1990; Searcy 1989; McGregor et al. 1992; Weary & Mountjoy 1992), and a recent paper has reviewed subsequent progress in avoiding pseudoreplication in experimental studies of bird song (Kroodsma et al. 2001). My objective here is ... to expand the discussion of behavioural experiments.   To this end, I identify some compromises any experimenter must make in justifying the biological independence of subjects, the external validity of conclusions, the multiple use of exemplars and subjects, and the effects of sample size on unsuspected bias.   These compromises make it less clear that any one design is universally optimal.   In some circumstances, it is appropriate to use each exemplar more than once and to test each subject more than once.   Although there is no ideal experimental design, I propose that there is an ideal way to report a behavioural experiment, one that explicitly identifies the compromises involved.

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