Estimate parameters for scaling of standard deviation with mean body size

Calculates parameters for a (log-log linear) scaling relationship between the mean and standard deviation of a species' mean body size. Given a table of species with known mean and standard deviation body sizes, fits a linear model of the form log(var(body_size)) ~ log(mean(body_size)) and extracts parameter estimates, which can then be used to estimate the standard deviation of body mass for a species based only on its mean body mass. See also Thibault et al. (2011) for this method applied to the Breeding Bird Survey.

Usage

get_sd_parameters(raw_size_data)

Arguments

raw_size_data

dataframe of species' mean and standard deviation body sizes; use the included raw_masses data table.

Value

list of $slope and $intercept from the linear model fit

References

• Thibault, K. M., White, E. P., Hurlbert, A. H., & Ernest, S. K. M. (2011). Multimodality in the individual size distributions of bird communities. Global Ecology and Biogeography, 20(1), 145–153. https://doi.org/10.1111/j.1466-8238.2010.00576.x