Resident Risk Assessment software
| Uncensor | Samplesize |
| Bootstrap |
The Uncensor program estimates the mean, standard deviation, variance, and the confidence interval on the mean of left-censored data sets. At present, the program can provide estimates for normal and two-parameter lognormal data sets. Large (N>20) and small (N<20) data sets can be handled.
The Uncensor program was revitalized by Dr. David Evans in collaboration with Dr. M.C. Newman. It was converted to a Windows-based program, graphic displays of data were added, and data entry was made easier.
BOOTSTRAP is designed to calculate a community NOEC (no observed effect concentration) using a bootstrap method. Starting with NOEC values for a set of representative species with respect to a certain toxicant, assume that the available data set is a random sample from some larger population of NOEC values. Another population with the same parameters as the unknown one can be built up by taking a large number of samples from the available data set. To resample a data set, one takes repeated samples ("resamples") with replacement and calculates parameter estimates for each sample. The mean and standard deviation of these estimates are then obtained.
Samplesize
This program calculates N, the minimum number of samples (or replicates) necessary to obtain a desired confidence level. The methods are outlined in Quantitative Methods in Aquatic Ecology by M.C. Newman pp 42-45.
This program estimates the HC5 and its 95% confidence interval from species senstivity data using a bootstrap method. The bootstrap approach has the advantage over parametric methods because it requires no assumption of a particular distribution for the data. The FORTRAN code was developed by Tyler Christensen.
