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User's Manual: SSD toolbox
Citation:
Etterson, M. User's Manual: SSD toolbox. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-18/116, 2020.
Impact/Purpose:
This model will be used by risk assessors and others to evaluate the spread and location of toxicity endpoints for Ecological Risk Assessment
Description:
The SSD tool is a tool for fitting species sensitivity distributions (SSD). It gathers together a variety of algorithms to support fitting and visualization of simple SSDs. The current version of the tool supports five distributions (normal, logistic, triangular, gumbel, and burr). When any of the first four distributions are chosen, the data are first common-log transformed (log10). When the burr distribution is chosen, the data are fit on their measurement scale. The tool also supports fitting distributions using three different methods (maximum likelihood, moment estimators, and graphical methods). However, the burr distribution can only be fit using maximum likelihood (Table 1).