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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)
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)
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)
To improve the clinical measurement of dyspnea, we developed a baseline dyspnea index that rated the severity of dyspnea at a single state and a transition dyspnea index that denoted changes from that baseline. The scores in both indexes depend on ratings for three different categories: functional impairment; magnitude of task, and magnitude of effort. At(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)
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)
An improved prognostic staging system is needed for patients with the acquired immunodeficiency syndrome (AIDS). To construct such a system, we analyzed the course of 117 consecutive adults who received a diagnosis of AIDS at Yale-New Haven Hospital from 1981 through 1987. The staging system was developed from the data on the first 76 patients, confirmed in(More)
OBJECTIVE To evaluate how well quality of life is being measured in the medical literature and to offer a new approach to the measurement. DATA SOURCES Original English-language articles having the term "quality of life" in their titles were identified from a recent Quality-of-Life Bibliography and from two MEDLINE searches. Articles were eligible for(More)