Presents the practical and statistical information needed to help investigators decide how large a sample to select from a population targeted for a health study or survey. Desgned to perform a cookbook function, the book uses explanatory text and abundant tabular calculations to vastly simplify the task of determining the minimum sample size needed to obtain statistically valid results. The objective is to assist those investigators, undertaking health studies at local or district level, who lack detailed knowledge of statistical methodology. Acknowledging that the size of a sample will depend on the aims, nature, and scope of the study, the first part of the book provides a practical framework for working through the steps of sample size determination once a proposed study and its objectives have been clearly defined. In six chapters, readers are introduced to a variety of situations in which minimum sample size must be determined, including studies of population proportion, odds ratio, relative risk, and disease incidence. Each situation is first defined in terms of the information required and then illustrated by a hypothetical example of a study objective and the questions that will need to be answered in order to determine the appropriate sample size. The solution to each problem is clearly stated, together with relevant explanatory notes. The second part of the book features more than 50 pages of tables that enable the reader to determine the sample size required, under simple random sampling, in a given type of study without recourse to complicated calculations. Each of the illustrative examples featured in the first part of the book includes a reference to one of these tables, thus showing investigators how to move from the objectives and design of a study to the rapid calculation of an appropriate sample size. Examples and tables were selected as representing many of the approaches most likely to be adopted in health studies.

chi eng fre spa.

per tur.

WHODOC

WHO monograph

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