BMC Medical Research Methodology

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	$\hat{λ} > λ$	$\hat{β} > β$	$\hat{λ} > λ$	$\hat{β} > β$
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%

Calculations were made on the replications where there was no problem of maximization. Abbreviations : TBE truncation-based estimator.

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