Study types

A clinical study is a research study using human subjects to evaluate biomedical or health-related outcomes. On the English version of this website, clinical studies are divided up into the subsidiary groups clinical trials, observational studies, diagnostic studies and qualitative studies.

Clinical trials

Clinical trials are sometimes called intervention studies or experimental studies. Within the framework of a clinical trial, study participants are exposed to some kind of intervention, for example a medicine, a medical device, a diet or a surgical method according to a previously agreed protocol. The purpose is to investigate or confirm the safety or effect of the therapy or method.

In a controlled clinical trial, the new therapy or method is compared with a control consisting of an established therapy or method, placebo or no measure at all. In a randomised controlled trial, the study participants are allocated randomly between the treatment groups.

Observational studies

Observational studies are sometimes called non-intervention studies, or non-experimental studies. No active measure is taken, instead the study participants are observed during current circumstances. Observational studies may, for example, consist of ecological or epidemiological investigations, cross-section investigations, cohort investigations or case-control investigations.

Diagnostic studies

Diagnostic studies investigate diagnostic tests aimed at identifying persons with a disease or health problem. The outcome of a diagnostic study has no immediate, direct value for the study participants. The concepts of sensitivity and specificity are often used to describe the reliability of a diagnostic test.

Qualitative studies

In qualitative studies, the research question is answered by interpreting events and development of categories or models that describe a phenomenon or a context, rather than by numbers and statistics. The most common way of working is through comprehensive interviews.

Other actors’ definitions of study types

MeSHexternal link, opens in new window and clinicaltrials.govexternal link, opens in new window use the terms clinical trials and observational trials, similar to the English version of kliniskastudier.se.

MeSH is an abbreviation of medical subject headings. It is a hierarchically organised vocabulary used to index scientific publications in registers such as PubMed. MeSH has been developed by the US National Library of Medicine.

Clinicaltrials.gov is a registration and result database operated by the US National Institutes of Health and contains information about clinical studies around the world.

The Swedish Agency for Health Technology Assessment and Assessment of Social Services (SBUexternal link, opens in new window) uses the terms intervention studies and observational studies in its English review templates.

On the Swedish version of kliniskastudier.se we use the terms "behandlingsstudie" and "observationsstudie".

Date created: 2017-11-14
Last published: 2018-11-13


Office for Clinical Studies

Östra Hamngatan 26
SE-411 09 Göteborg


Phone: +46 (0)31 757 41 75

E-mail: kliniskastudier@vr.se


Would you like to subscribe to news, good examples or calendar events from clinicalstudies.se?

Clinical Studies Sweden - a collaboration between The Swedish Research Council and the Swedish Association of Local Authorities and Regions.