The fit of allometric models with either a fixed (subscript 0.75) or an empirical scaling exponent (subscript a).

Both the coefficient of determination (r2) and the correlation coefficient (r with its standard deviation SD) between the actual and model-predicted values are shown. Column a shows the average scaling exponent when it was empirically estimated. Each cell in the table shows the mean values for 600 simulated datasets where the number of observations (N) was either 20 or 120. SD indicates the amount of variability in the model fit obtained (columns after r) or in the estimate of a (column after a).