摘要:

AbstractThe advantages and drawbacks of basing treatment comparisons on observational data are discussed. Recommendations are made for minimizing bias when basing comparisons on computerized data banks. A specific example is given concerning treatment following severe head injury.

ISSN:0277-6715    

DOI:10.1002/sim.4780050202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe performances of four published risk prediction systems for sudden infant death syndrome (SIDS) were compared for the 34 cases of SIDS and 48 explained deaths among a cohort of all births in the U.K. during one week in April 1970.With cut‐points for the scores which would include about 20 per cent of the population, the sensitivities of the scoring methods ranged from identifying 40 per cent of the explained deaths to 70 per cent of SIDS. The highest sensitivities were achieved with the Sheffield ‘at birth’ system and a system based on both data from Oxford and general observations from the literature, with the latter system providing the most powerful predictor of SIDS for the study s

ISSN:0277-6715    

DOI:10.1002/sim.4780050203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe duration of the detectable preclinical phase of disease, which we call the sojourn time, is an important quantity to consider when recommending frequency of screens and investigating the natural history of the disease. In this paper, we propose a matched case‐control methodology for screening data for joint estimation of the sojourn time distribution and the false negative rate of the screening test. The approach is based on a conditional likelihood for matched sets that involves a comparison of the screening histories of cases and controls. We illustrate the methodology with the data from the Aberdeen screening programme for cervical cancer by the Pap smear. We consider a number of different parametric forms for the sojourn time distributio

ISSN:0277-6715    

DOI:10.1002/sim.4780050204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractInfant mortality data for England and Wales, cross‐classified by mother's age, parity and social class have been published on two occasions, the first giving the relevant data for 1949/50, the second for 1975, some 25 years later. Published analyses of these separate data sets have been based on graphical and tabular analysis. This paper develops the methodology from an earlier paper by Murrellset al.1to the analysis of the neonatal dat

ISSN:0277-6715    

DOI:10.1002/sim.4780050205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractInfant mortality data for England and Wales, cross‐classified by mother's age, parity and social class have been published on two occasions, the first giving the relevant data for 1949/50, the second for 1975, some 25 years later. Published analyses of these separate data sets have been based on graphical and tabular analysis. This paper describes the application of logit models using the methodology presented by Murrellset al.1to investigate post‐neonatal dea

ISSN:0277-6715    

DOI:10.1002/sim.4780050206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIn geographical epidemiology, the correlation between two variables is often studied, using as basic units those zones for which these variables are available. However, because of their geographical contiguity, it could be misleading to consider each of these zones as independent statistical units. Moreover, spatial distributions (either of the factor or of the disease) are often distributed in relatively simple patterns; these patterns may induce strong correlations. Thus, the general pattern of the spatial distribution of the variables should be investigated before any attempt to infer epidemiological interpretation of a relationship. This paper presents an algorithm to construct contiguous groupings which are similar enough with regard to one of the two variables considered and to thus divide the original set of geographical areas into contrasting zones. The algorithm is easy to compute and allows mapping of the geographical distribution of the variable studied. It also lessens the risk of duplication of basic information by reducing the autocorrelation of one of the variables.

ISSN:0277-6715    

DOI:10.1002/sim.4780050207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractEstimates of analyte concentrations, obtained by immunoassay, have error distributions which are generally underestimated. Better estimates, which take into account the distribution of the response metameter of the calibration curve and uncertainties associated with the location of the fitted curve, have been obtained by computer simulation using practical immunoassay data. The increased use of curve‐fitting software in automated immunoassay equipment has prompted the investigation of reported analyte concentration distributions for three commonly used functions, namely the logit‐log, the 4‐parameter logistic and the fourparameter Amersham models. The simulation model is of potential value for a variety of situa

ISSN:0277-6715    

DOI:10.1002/sim.4780050208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe advent of cheap and powerful microcomputers provides opportunities for improving the teaching of statistics in medicine. This paper describes a practical exercise in which students study the concept of statistical significance using a simple computer program which simulates a clinical trial. The students are required to make decisions about patients with incomplete data and form contingency tables for analysis. This includes analysing contingency tables with several cells having small expected frequencies. The results from 25 groups of students are collected together and presented to the class. Two null hypotheses are tested, one of which is true. For the true null hypothesis the group is likely to produce, by chance, at least one significant result at the 0.05 level. For the false null hypothesis only a minority of results will be significant, because the sample size is small. This leads to a discussion of the concept of statistical significance. The simulation model is described and the advantages and potential of this type of teaching are discussed.

ISSN:0277-6715    

DOI:10.1002/sim.4780050209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780050211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780050212

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY