A genetic and epidemiological study is especially important in those hereditary diseases for which no effective treatment is known, since then genetic counselling is the only means of prevention. The progressive muscular dystrophies are typical conditions of this sort. Knowledge of the type of hereditary transmission for a given form of muscular dystrophy is the basis for correct genetic progno...

Sample-size determination is often an important step in planning an epidemiological study. There are several approaches to determining sample size. It depends on the type of the study. Descriptive, observational and randomized controlled studies have different formulas to calculate sample size. In this article, we discuss the formulas that can help to estimate sample size in an epidemiological ...

Cluster sampling has recently been used to estimate the mortality in various conflicts around the world. The Burnham et al. (2006) study on Iraq employs a new variant of this cluster sampling methodology. The stated methodology of Burnham et al. (2006) is to (1) select a random main street, (2) choose a random cross street to this main street, and (3) select a random household on the cross stre...

OBJECTIVE To compare refraction measured before and after pharmacologic cycloplegia. METHODS This study used preliminary data from the Beaver Dam Offspring Study, which includes adult children of participants in the population-based Epidemiology of Hearing Loss Study of older adults living in Beaver Dam, Wisconsin. Data were available for 5018 eyes of 2529 participants. Refraction was defined...

Epidemiological studies have proved invaluable for identifying environmental risk factors and gene-environment interactions in the development of hypertension and other chronic diseases. Now, after several decades, the solid contributions of longitudinal and cross-national studies of random population samples are well established. The art and science of clinical trials have achieved a high leve...

Correspondence to: Dr M J Nieuwenhuijsen, Imperial College of Science, Technology and Medicine, London, UK; m.nieuwenhuijsen@imperial. ac.uk _________________________ Q uestionnaires are frequently used in the exposure assessment of occupational and environmental epidemiological studies. Questionnaires may be the method of choice for assessing exposure because no other sources of information ar...

The recent publication of the human genome sequence is widely thought to offer the opportunity for a radical change in our understanding of a variety of common human diseases. One particular hope is that the new information available from the genome sequencing effort will facilitate the conduct of population genetic studies, which will discover the genetic variants responsible for 'complex' or ...

Analysis of morbidity statistics in Government hospitals in Ceylon reveals that among the causes of morbidity, Pyrexias of Unknown Origin (P.U.O.) rank second only to the enteric diseases. The contribution of leptospirosis to the group of P.U.O. has not been evaluated. Awareness of this disease in Ceylon was created by Falisevac and Arumainayagam (1959). They wrote, " Since the climatic, geogra...

The paper addresses a formal de®nition of a confounder based on the qualitative de®nition that is commonly used in standard epidemiology text-books. To derive the criterion for a factor to be a confounder given by Miettinen and Cook and to clarify inconsistency between various criteria for a confounder, we introduce the concepts of an irrelevant factor, an occasional confounder and a uniformly ...

Interpretation of the guidelines for ethical considerations in epidemiological studies requires defining a position of delicate balance. The goal must be to protect the rights, the health, and the dignity of study participants to the extent possible, while at the same time placing as few inhibitions as possible on the conduct of the research. The end result must therefore be a compromise, becau...