This program originated at Montana State University and
has been modified by data processing staffs at the Duluth
and Athens National Exposure Research Laboratories.
The Trimmed Spearman-Karber estimate of the LC50
is obtainable for most experiments. In order to
estimate an LC50 the only requirement is that at
least one mortality proportion must be less than or equal
to 50% and at least one must be greater than or equal to 50%.
That is, it is not possible to calculate the
LC50 by the Spearman-Karber Method if the mortality
proportions are all less than 50% or are all over
For reference, cite: Hamilton, M.A., R.C. Russo, and R.V. Thurston, 1977.
Trimmed Spearman-Karber Method for Estimating Median Lethal
Concentrations in Toxicity Bioassays. Environ. Sci. Technol.
11(7): 714-719; Correction 12(4):417 (1978).