Software Open Access
ssdtools is an R package to plot and fit Species Sensitivity Distributions (SSD). SSDs are cumulative probability distributions which are fitted to toxicity concentrations for multiple species. The ssdtools package uses Maximum Likelihood to fit log-normal, log-logistic, log-Gumbel, Gompertz, gamma or Weibull distributions. Multiple distributions can be averaged using Information Criteria. Confidence intervals on fits and hazard concentrations are produced by bootstrapping.