In a controlled observational cohort study, two groups of subjects are selected from two populations that (hopefully) differ in only one characteristic at the start. The groups of subjects are studied for a specific period and contrasted at the end of the study period. For instance, smokers and nonsmokers are studied for a period of 10 years, and at the end the proportions of smokers and nonsmo...

OBJECTIVE To determine feasibility and estimate the effect of a 10-week tai chi chuan (TCC) intervention on anxiety and sleep quality in young adults. PARTICIPANTS Seventy-five adults (18-40 years) from a predominately undergraduate midsized university. METHODS This was an assessor blinded, randomized feasibility trial, and participants were randomized into one of three groups: 10 weeks of ...

That psychologists conduct sound research is important whatever their research areas, but it is especially important when the results of this research have a substantial impact on people’s lives. This is the case for intervention research, the findings of which may influence the type of treatments people receive. Sound intervention research is critical for determining what treatments are benefi...

OBJECTIVES To consider methods and related evidence for evaluating bias in non-randomised intervention studies. DATA SOURCES Systematic reviews and methodological papers were identified from a search of electronic databases; handsearches of key medical journals and contact with experts working in the field. New empirical studies were conducted using data from two large randomised clinical tri...

Correspondence to: Prof. T S Kristensen, National Institute of Occupational Health, Lerso Parkalle 105, DK-2100 Copenhagen O, Denmark; [email protected] _________________________ T he proportion of intervention studies in occupational epidemiology has been growing rapidly in recent years. This is a positive trend, which makes it necessary to discuss a number of theoretical, methodological, and practic...