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Biomedical subjects

J Nedelman

Publications and source records attributed to J Nedelman.

2 recordsLinked to original sources

Quantitative PCR with internal controls.

We examine the use of internal controls for estimating the expected initial copy number of the target in a polymerase chain reaction (PCR). We base our investigation on an extended branching-process model. In terms of that model, we delineate the necessary assumptions for this methodology to yield approximately unbiased answers, and we provide means for testing some of those assumptions. We show how to design a series of PCRs to attain optimal precision of the estimate. We provide an algorithm for conducting the statistical analysis of the data, including a formula for a confidence interval for the unknown expected initial copy number.

Algorithms

Modelling length bias in a longitudinally-linked record system of HIV cases.

We compare numbers of hospital admissions for intravenous drug using (IVDU) HIV patients and other HIV patients in acute-care facilities in New York State. Data consist of routinely collected hospital-discharge reports from New York's Statewide Planning and Research Cooperative System, linked into longitudinal case histories. Because recognition of an IVDU depends on an opioid diagnosis on any record in the case history, the observed distribution of the number of admissions per case for recognized IVDU's is biased towards greater numbers of admissions. We develop and apply a model to overcome this biasing. Our findings reveal that the mean numbers of admissions for the two groups differ significantly, but less so than without recognition of the length biasing.

Bias