Look before you leap: stratify before you standardize

Article Abstract:

It is advisable to stratify data to look at patterns of age-specific rates prior to applying age standardization in epidemiology. Conditions for valid comparison depend on the kind of measurement used for comparison. Canadian empirical data show age-specific rates do not always keep to a consistent pattern over time. A mathematical model is presented for showing conditions in which age standardization can be used to summarize age-specific rates for comparison purposes over calendar time.

Canada, Standards, Methods, Asthma, Health surveys, Hospital utilization, Epidemiology, Medical statistics, Statistics (Mathematics)

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Slopes of a receiver operating characteristic curve and likelihood ratios for a diagnostic test

Article Abstract:

The author in this paper aimed to clarify the slope of a receiver operating characteristic (ROC) curve and the likelihood ratio. It pointed out the tangent at a point on the curve, the slope between the origin and a point on the curve, and the slope between two points on the curve. The paper further illustrated the relations between slopes and likelihood ratios.

Interpretation and construction, International aspects, Multivariate analysis, Diagnosis, Noninvasive, Noninvasive diagnosis, Ratio analysis

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Role of placental tissues in the intrauterine transmission of hepatitis B virus

Article Abstract:

The hepatitis B virus may be transmitted through the placenta from one cell to another rather than being transmitted by blood. Antibodies against the virus may carry it from one cell to another because the cells have receptors for the antibody.

Infection, Disease transmission, Placenta, Hepatitis B virus

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