Relative cost of change in fineness.

Raw (α) and standardized (α') effects of fineness (f) on Umax for the laminar and transitional model of rigid-body drag. The coefficients are from a mechanistic and not regression model, and thus are truly causal (in the world of the model). The ρ aw coeffcients are the slopes of the curves in Fig. 3C, D at fineness 1–10. Except at f = 1, these approximately equal the percent increase in swimming speed given a unit increase in f. The standardized coefficients are standardized effect sizes represent the average change (or effect) in standard deviation units.