Journal of Clinical Bioinformatics

Table 2 Univariate Marker Results

From: The impact of sample storage time on estimates of association in biomarker discovery studies

	n= 75						n= 200
	increase over time			decrease over time			increase over time			decrase over time
t = 0
	0.309	0.309	0.309	0.309	0.308	0.308	0.308	0.308	0.307	0.307	0.308	0.308
se.emp	0.005	0.005	0.005	0.005	0.005	0.005	0.003	0.003	0.003	0.003	0.003	0.003
rel.bias	0.029	0.029	0.029	0.03	0.028	0.028	0.026	0.026	0.024	0.024	0.026	0.026
rel.bias.sd	0.566	0.566	0.568	0.571	0.568	0.563	0.343	0.342	0.343	0.341	0.342	0.34
t = 5
	0.288	0.305	0.272	0.334	0.312	0.356	0.287	0.304	0.271	0.331	0.312	0.355
se.emp	0.005	0.005	0.005	0.006	0.005	0.006	0.003	0.003	0.003	0.003	0.003	0.004
rel.bias	-0.041	0.015	-0.092	0.112	0.042	0.186	-0.044	0.013	-0.096	0.105	0.039	0.184
rel.bias.sd	0.527	0.559	0.5	0.617	0.576	0.65	0.319	0.337	0.302	0.368	0.346	0.393
t = 10
	0.269	0.269	0.269	0.362	0.361	0.361	0.268	0.268	0.268	0.36	0.361	0.361
se.emp	0.005	0.005	0.005	0.006	0.006	0.006	0.003	0.003	0.003	0.004	0.004	0.004
rel.bias	-0.103	-0.103	-0.103	0.208	0.204	0.204	-0.106	-0.106	-0.107	0.199	0.202	0.202
rel.bias.sd	0.493	0.493	0.495	0.671	0.667	0.66	0.298	0.297	0.298	0.4	0.401	0.399

Mean values of the maximum likelihood estimates of β = 0.3 after t = 0, 5, and 10 years for the various degradation functions, with empirical (se.emp) standard error and the relative bias . Simulations were performed with μ = -3, and sample sizes n = 75 and n = 200. Function b₁ corresponds to a linear change, b₂ exponential change and b₃ logarithmic change in marker levels over time.

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