Plots of the models used in the simulation.

<p>Group A (top row): detection functions for four line transect senarios with no covariates (solid lines) and their constituent mixture components (dashed lines). Group B (second row): pdfs for four point transect simulations with no covariates (solid lines), with associated component pdfs (dashed lines), rescaled so the area under each curve is one; the detection functions are as in the top row. Group C (third row): two 3-point mixture scenarios for non-covariate line transect data, again with their constituent mixture components (dashed lines). Group D (fourth row): two covariate model scenarios, the first two panels are for a binary covariate scenario, the second two for a continuous covariate scenario; first panels in each pair show the detection function averaged over the covariates (along with the mixture components, similarly averaged) and the second panels show marginal detection functions with the levels (or quartiles) of the detection function. Group E (fifth row): exponential power series model and a 2-point mixture of hazard-rate function (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118726#pone.0118726.s002" target="_blank">S2 Appendix</a> for formulation) for two line transect scenarios.