Non-differential measurement error does not always bias diagnostic likelihood ratios towards the null

Non-differential measurement error does not always bias diagnostic likelihood ratios towards the null

Diagnostic test evaluations are susceptible to random and systematic error. Simulated non-differential random error for six different error distributions was evaluated for its effect on measures of diagnostic accuracy for a brucellosis competitive ELISA. Test results were divided into four categories: < 0.25, 0.25-0.349, 0.35-0.499, and > or = 0.50 proportions inhibition for calculation of like...

Bagging Does Not Always Decrease Mean Squared Error

Bagging is a device intended for reducing the prediction error of learning algorithms. In its simplest form, bagging draws bootstrap samples from the training sample, applies the learning algorithm to each bootstrap sample, and then averages the resulting prediction rules. Heuristically, the averaging process should reduce the variance component of the prediction error. This is supported by emp...

Does nondifferential misclassification of exposure always bias a true effect toward the null value?

The authors present some examples to demonstrate that in certain nondifferential misclassification conditions with polychotomous exposure variables, estimates of odds ratios for categories at intermediate level of risk can be biased away from the null or can change direction. In addition, the authors present two examples to demonstrate that the slope of the dose-response trend for the true dist...

Making sense of diagnostic test likelihood ratios.

Likelihood ratios: getting diagnostic testing into perspective.

In modern medicine, sophisticated laboratory tests and imaging studies are often emphasized at the expense of history and physical examination, rather than complementing clinical assessment. Ancillary testing often fails to advance the diagnostic process, and increases patient risk and the expense of medical care. The relative value of clinical evaluation and technological methods is rarely con...