BOOTSTRA

BOOTSTRA 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. With an adequate sample size and enough iterations, estimates can be quite accurate.

If the program is on a diskette, change the current drive to the drive the diskette is in and type BOOTSTRA.  The program will first prompt you for the data set size (up to 100), the size of the resamples (up to 500; this can be larger than the data set size), the number of iterations (up to 1000), and the percentile to use for the NOEC (as a decimal fraction, e.g., 0.5, 0.10, etc.).
You will then be prompted for the names of the data file and the file you want the results printed to. Be sure to include the complete filenames, including the drive name (e.g., B:RESULT.DAT).
To view the results, edit the result file.

The FORTRAN program can be customized to accommodate larger data files or perform more iterations by changing the appropriate DIMENSION statements.