pe_avg_cv: Estimate the average-CV portfolio effect

In seananderson/ecofolio: Tools to quantify metapopulation portfolio effects

Description

Takes a matrix of abundance or biomass data and returns various estimates of the average-CV portfolio effect. Options exist to detrend the time series data.

Usage

pe_avg_cv(x, detrending = c("not_detrended", "linear_detrended",
  "loess_detrended"), ci = FALSE, boot_reps = 500, na.rm = FALSE)

Arguments

x	A matrix or dataframe of abundance or biomass data. The columns should represent different subpopulations or species. The rows should represent the values through time.
detrending	Character value describing if (and how) the time series should be detrended before estimating the portfolio effect. Defaults to not detrending.
ci	Logical value (defaults to FALSE). Should a 95% confidence interval be calculated using a bootstrap procedure? Returns the bias-corrected (bca) version of the bootstrap confidence interval.
boot_reps	Number of bootstrap replicates.
na.rm	A logical value indicating whether NA values should be row-wise deleted.

Details

This version of the portfolio effect consists of dividing the mean of the coefficient of variations (CV) of all individual subpopulations (assets) by the CV of the combined total population.

Value

A numeric value representing the average-CV portfolio effect. If confidence intervals were requested then a list is returned with the portfolio effect pe and 95% bootstrapped confidence interval ci.

References

Doak, D., D. Bigger, E. Harding, M. Marvier, R. O'Malley, and D. Thomson. 1998. The Statistical Inevitability of Stability-Diversity Relationships in Community Ecology. Amer. Nat. 151:264-276.

Tilman, D., C. Lehman, and C. Bristow. 1998. Diversity-Stability Relationships: Statistical Inevitability or Ecological Consequence? Amer. Nat. 151:277-282.

Schindler, D., R. Hilborn, B. Chasco, C. Boatright, T. Quinn, L. Rogers, and M. Webster. 2010. Population diversity and the portfolio effect in an exploited species. Nature 465:609-612. doi: 10.1038/nature09060.

Examples

data(pinkbr)
pe_avg_cv(pinkbr[,-1], ci = TRUE)
pe_avg_cv(pinkbr[,-1], detrending = "loess_detrended", ci = TRUE)

seananderson/ecofolio documentation built on May 29, 2019, 4:25 p.m.