We have put together a small R package (nsecR) that will enable you to compute a No Significant Effect Concentration from a fitted C-R model. In addition, the program will instantly compute a model-avereraged NSEC (or maNSEC) if additional C-R functions are specified.
The package is NOT on CRAN – it must be installed from a tar.gz file. Click here to downlaod the nsecR package.
The NSEC is very similar in spirit to the NOEC in that we wish to determine the largest concentration for which the expected response is statistically insignificant to the expected control response.