BACKGROUND Cluster-randomized trials, in which health interventions are allocated randomly to intact clusters or communities rather than to individual subjects, are increasingly being used to evaluate disease control strategies both in industrialized and in developing countries. Sample size computations for such trials need to take into account between-cluster variation, but field epidemiologis...

BACKGROUND Random errors in measurement of a risk factor will introduce downward bias of an estimated association to a disease or a disease marker. This phenomenon is called regression dilution bias. A bias correction may be made with data from a validity study or a reliability study. AIMS AND METHODS In this article we give a non-technical description of designs of reliability studies with e...

Thc SEC developcd this statcment 1)1' revicwing kCI' educllional and historical documcl1ls of AOTA. A draft of this papel' was distributcd bmadly for review ancl commel1l to kel' constitucl1l groups ancl leadcrs of the Associarion, Two cycles of review were completed before the statement Ivas submitted to the Representarive Assembly in 1993. The intent of the statement is nor to delineate all p...

A pilot study asks whether something can be done, should the researchers proceed with it, and if so, how. However, a pilot study also has a specific design feature; it is conducted on a smaller scale than the main or full-scale study. In other words, the pilot study is important for improvement of the quality and efficiency of the main study. In addition, it is conducted in order to assess the ...

pioneering in a dynamic environment is among the issues which most of the organizations, especially knowledge-based institutions will encounter. for using and exploiting the opportunities and also for overcoming threats, there should exist some innovations in the modern technologies domain. therefore, for fulfilling this important issue, organizations are required to monitor inside and outside ...