Description Usage Arguments Details Value References Examples
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.
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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 |
boot_reps |
Number of bootstrap replicates. |
na.rm |
A logical value indicating whether |
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.
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
.
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.
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