, Volume 10, Issue 1, pp 25–34

Estimating the 5-Percentile of the Species Sensitivity Distributions Without Any Assumptions about the Distribution

  • Nelly Van der Hoeven


A non-parametric method is described to estimate the hazardeous concentration for p% of the species, the HCp, and the confidence limits for this value, the HCp(α). For this method, all observed sensitivities are ordered from high to low sensitivity. The HC5 is the k-th observation were k is the largest integer below 0.05×(n+1). It is described how the HCp(α) can be calculated. A table is presented for easy calculation of several conservative confidence limits for the HC5. For the HC5(0.05), a second table is presented which can be used to interpolate between the conservative estimate of the HC5(0.05) and the next higher observed concentration. The non-parametric HC5 and HC5(0.05) estimation is illustrated with an example of sensitivity data on malathion. For this data set, the log-normal HC5 and HC5(0.05) estimations appear to be conservative compared with the non-parametric estimate. It is stressed that HC5 and HC5(0.05) estimates will often be much more affected by the non-randomness of the species set for which sensitivity data are available than by the choice of the statistical method.

beta distribution hazardous concentration 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Nelly Van der Hoeven
    • 1
  1. 1.ECOSTATLeidenThe Netherlands

Personalised recommendations