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At least 271 records · Page 15Linked to original sources
PubMed1998

Statistical methods in epidemiology: a comparison of statistical methods to analyze dose-response and trend analysis in epidemiologic studies.

Evaluation of various statistical methods to describe accurately associations between exposures and disease are constantly being explored. Spline regression has been suggested as an alternative to using categorized variables in studies of disease etiology, as it uses all data points to estimate the shape of the association between a given exposure and disease outcome. It has been proposed that this method is especially beneficial when associations are concentrated in a small range of the overall distribution of the exposure. In this study, we use data from a large case-control study of colon cancer to evaluate associations obtained from logistic regression models that use spline regression for main exposure and confounder effects with those that use categorized variables for main exposure. Our results show that for variables for which the association appears to be linear, such as body size and dietary intake of calcium, fiber, and cholesterol, associations are similar when estimates are generated from spline or categorized variable models. For other variables, such as total energy intake, for which associations appear to be strongest in the upper end of the distribution, estimates of association appear to be conservative when using categorized variables. The data also suggest that selection of cut points for the categorized variables may have an impact on the associations observed. Spline regression appears to be useful to estimate the shape of the association between a given exposure and disease and may provide guidance as to the appropriateness of using categorized variables. The risk estimates from spline regression appear to be similar to those from traditional categorical methods. When effects are large or rapidly changing, spline models may more appropriately describe the association.

Adult↗
PubMed2003

Paper critique as an educational method in epidemiology.

A common method in the teaching of epidemiology at the London School of Hygiene and Tropical Medicine is 'paper critique'. This refers to a close reading of published research articles, in which students are asked to assess their coherence and validity. The intention is to improve the students' analytic and writing skills, as well as acting as a form of summative assessment. In this paper, the author links his experience of this method to concepts such as rhetoric, myth and semiology, and uses them to try to develop paper critique as an educational method.

Comprehension↗
PubMed1982

Double standards, scientific methods, and epidemiologic research.

Because suspected noxious agents can seldom be tested experimentally in people, epidemiologic investigation of the causes of disease depends on observational procedures, of which the most prominent types are cohort and case-control studies. In these studies the compared agents cannot be assigned experimentally, but many other basic experimental principles that could be employed are often overlooked, including verification of quality and accuracy in raw data, avoidance of major biases in comparison, vigilance in checking for methodologic errors, and maintenance of a careful distinction between research data that generate hypotheses and the new data needed to test these hypotheses. The problems that result when these principles are overlooked can be alleviated if etiologic research is performed and evaluated with the same standards used in other branches of science.

Diagnosis↗
PubMed1990

Analysis of clinical and food-borne isolates of Listeria monocytogenes in the United States by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations.

To investigate the microbiology and epidemiology of the 1,700 sporadic cases of listeriosis that occur annually in the United States, we developed a multilocus enzyme electrophoresis (MEE) typing system for Listeria monocytogenes. We studied 390 isolates by MEE. Eighty-two electrophoretic types (ETs) were defined. Two distinct clusters of ETs, ET group A (ETGA) and ET group B (ETGB), separated at a genetic distance of 0.440, were identified. Strains of ETGB were associated with perinatal listeriosis (P = 0.03). All strains of H antigen type a were in ETGA, while all strains of H antigen type b were in ETGB. Among 328 clinical isolates from cases of literiosis, 55 ETs of L. monocytogenes were defined. Thirty-four ETs were identified among 62 isolates from food products. The mean number of strains per ET (5.2) was significantly higher among clinical isolates than among food-borne isolates. Examination of isolates from outbreaks further documented the link between cases and contaminated food products. In one investigation, we found 11 different ETs, ruling out a single common source as a cause of that outbreak. By examining a large number of isolates collected over a specified time in diverse geographic locations in the United States, we have begun to establish a baseline for the study of the epidemiology of listeriosis by MEE.

Bacterial Typing Techniques↗