Three consecutive animals survive at the upper bound of dosing, where the upper bound of testing is the highest dose given to the animals, based on regulatory needs. Normally, the upper bound of dosing is 2000 or 5000 mg/kg.
Five reversals occur in any six consecutive animals tested;
At least four animals have followed the first reversal and two likelihood ratios, which compare the LD50 estimate with LD50 values above and below (Figure 4), exceed a critical value of 2.5. In this example, a likelihood is a probability of seeing a certain pattern of survivals or deaths based on hypothetical combinations of LD50 and slope consistent with the data.