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An omnibus index offers a single summary expression for a fourfold table of binary concordance among two observers. Among the available other omnibus indexes, none offers a satisfactory solution for the paradoxes that occur with p0 and kappa. The problem can be avoided only by using ppos and pneg as two separate indexes of proportionate agreement in the(More)
We performed a Monte Carlo study to evaluate the effect of the number of events per variable (EPV) analyzed in logistic regression analysis. The simulations were based on data from a cardiac trial of 673 patients in which 252 deaths occurred and seven variables were cogent predictors of mortality; the number of events per predictive variable was (252/7 =)(More)
In a fourfold table showing binary agreement of two observers, the observed proportion of agreement, p0, can be paradoxically altered by the chance-corrected ratio that creates kappa as an index of concordance. In one paradox, a high value of p0 can be drastically lowered by a substantial imbalance in the table's marginal totals either vertically or(More)
The opinions set forth in this report are those of the committee members and do not represent the Food and Drug Administration in any way. R osacea is well recognized as a chronic cuta-neous disorder primarily of the convexities of the central face (cheeks, chin, nose, and central forehead), often characterized by remissions and exacerbations. Based on(More)
The analytical effect of the number of events per variable (EPV) in a proportional hazards regression analysis was evaluated using Monte Carlo simulation techniques for data from a randomized trial containing 673 patients and 252 deaths, in which seven predictor variables had an original significance level of p < 0.10. The 252 deaths and 7 variables(More)
OBJECTIVE To determine the frequency and temporal changes in application of seven accepted methodological standards for the evaluation of diagnostic tests. DATA SOURCES A search of the MEDLINE database yielded 1302 articles about diagnostic test studies, during a 16-year secular interval, 1978 through 1993, in four prominent general medical journals. (More)
Boundaries for delta, representing a "quantitatively significant" or "substantively impressive" distinction, have not been established, analogous to the boundary of alpha, usually set at 0.05, for the stochastic or probabilistic component of "statistical significance". To determine what boundaries are being used for the "quantitative" decisions, we reviewed(More)
We propose a short, simple approach that can be used by general internists to routinely screen the functional status of elderly patients in office practice. The approach relies on checking a limited number of targets that are commonly dysfunctional but often unappreciated when conventional histories and physical examinations are done for elderly patients.(More)
PURPOSE To review the principles of multivariable analysis and to examine the application of multivariable statistical methods in general medical literature. DATA SOURCES A computer-assisted search of articles in The Lancet and The New England Journal of Medicine identified 451 publications containing multivariable methods from 1985 through 1989. A random(More)