that maximum likelihood estimates of k can be biased upward by small sample size or under - reporting of zero - class events ,
Confidence intervals <*> tend to exhibit coverage below the nominal level , with overestimates of k
Results show that maximum likelihood estimates of k can be biased upward by small sample size or under - reporting of zero - class events , but are not biased downward by any of the factors considered .
Confidence intervals estimated from the asymptotic sampling variance tend to exhibit coverage below the nominal level , with overestimates of k comprising the great majority of coverage errors .