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Table 6 Simulation results: proportion of replications where the maximum likelihood estimator is larger than the true value of the parameter for the Weibull model

From: Estimating time-to-onset of adverse drug reactions from spontaneous reporting databases

     Naive estimator TBE
λ β p n λ ̂ >λ β ̂ >β λ ̂ >λ β ̂ >β
0.05 0.5 0.25 100 100% 100% 81.4% 71.9%
    500 100% 100% 64.6% 64.5%
0.05 0.5 0.50 100 100% 100% 63.3% 60.1%
    500 100% 100% 53.4% 51.0%
0.05 0.5 0.80 100 100% 99.6% 52.0% 53.3%
    500 100% 100% 48.6% 51.6%
1 0.5 0.25 100 100% 100% 79.3% 76.0%
    500 100% 100% 62.0% 61.2%
1 0.5 0.50 100 100% 100% 65.9% 64.6%
    500 100% 100% 53.8% 51.8%
1 0.5 0.80 100 100% 99.5% 52.7% 52.2%
    500 100% 100% 51.9% 50.6%
0.05 2 0.25 100 100% 98.1% 52.1% 61.6%
    500 100% 100% 52.2% 53.7%
0.05 2 0.50 100 100% 94.2% 51.6% 53.3%
    500 100% 100% 50.6% 51.0%
0.05 2 0.80 100 100% 85.4% 56.1% 55.8%
    500 100% 97.9% 52.2% 49.6%
1 2 0.25 100 100% 98.2% 56.2% 62.5%
    500 100% 99.9% 50.1% 54.8%
1 2 0.50 100 100% 94.3% 53.9% 54.2%
    500 100% 99.9% 47.1% 48.1%
1 2 0.80 100 100% 85.3% 54.1% 54.2%
    500 100% 97.9% 52.7% 52.2%
  1. Calculations were made on the replications where there was no problem of maximization. Abbreviations : TBE truncation-based estimator.