Statistics in medicine
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Statistics in medicine · Apr 1991
ReviewMultiple imputation in health-care databases: an overview and some applications.
Multiple imputation for non-response replaces each missing value by two or more plausible values. The values can be chosen to represent both uncertainty about the reasons for non-response and uncertainty about which values to impute assuming the reasons for non-response are known. This paper provides an overview of methods for creating and analysing multiply-imputed data sets, and illustrates the dramatic improvements possible when using multiple rather than single imputation. A major application of multiple imputation to public-use files from the 1970 census is discussed, and several exploratory studies related to health care that have used multiple imputation are described.
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A few large clinical information databases have been established within larger medical information systems. Although they are smaller than claims databases, these clinical databases offer several advantages: accurate and timely data, rich clinical detail, and continuous parameters (for example, vital signs and laboratory results). ⋯ In addition, practice databases can be used to identify subjects for prospective studies. Further methodologic developments are necessary to deal with the prevalent problems of missing data and various forms of bias if such databases are to grow and contribute valuable clinical information.
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Statistics in medicine · Feb 1991
ReviewIdentifying the fertile phase of the human menstrual cycle.
The identification of the human fertile phase as the time during which a woman or a couple may conceive is elusive. The fertile time depends on many factors in each individual menstrual cycle and may be said to be more of a statistical than a physiological entity. This paper reviews the application of statistical methods to three areas related to conception and the fertile phase. ⋯ Direct estimation of such probabilities is impractical; instead, resort must be made to estimation by maximum likelihood of the parameters of specially constructed models. Suitable models are described. Finally, the need for a new prospective study of the probability of conception in relation to the markers of the fertile phase used in the symptothermal method of NFP is discussed.
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Statistics in medicine · Dec 1990
Group sequential designs using a family of type I error probability spending functions.
Performing planned or unplanned interim analyses on accumulating data in clinical trials is a frequent practice. In this paper, we propose a general one-parameter family of type I error probability spending functions to construct customized group sequential boundaries with unequal increments in information time. This proposed family generalized the spending functions of Lan and DeMets1 and Kim and DeMets.2 We give an example to illustrate the use of this family.
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Statistics in medicine · Sep 1990
What statistics should we teach medical undergraduates and graduates?
It is suggested that the emphasis on teaching statistics to medical undergraduates has usually been quite wrong: that the courses have become much too long, too detailed, and irrelevant to the needs of the majority. Examples are given which may help to introduce the basic concepts which all medical (and dental) undergraduates require, and which form a basis for the more traditional teaching of analytical methods to the appropriate subset who proceed to undertake medical research.