Understanding research

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Topics covered on this page include:

  • Citations
  • Research glossary


All sources of information, such as research papers, articles, books or web pages have a citation i.e. a unique descriptive reference which allows the source to be accurately identified and located. Scientific citations relating to research papers can be written in several different ways, but they will always include the following elements:

  • Title of the article
  • Who wrote it:
    Multiple authors are listed in a sequence reflecting the extent of their contribution, or alphabetically where they made equal contributions. ‘Et al’ is used when the names of only certain authors from a team are given and is an abbreviation of the latin for ‘and others’.
  • Where it was published:
    Title of journal, volume no., issue no. (if necessary) and page numbers (optional).

Here is a typical citation, followed by the translation:
Hughes SL, Smith A, Relton C. Homeopathy service in an NHS hospital breast cancer clinic: outcome study. Breast Cancer Research, 2008; 10 (2): 93.

Article called ‘Homeopathy service in an NHS hospital breast cancer clinic: outcome study’ written by Hughes, Smith and Relton. Published in 2008 in the journal, ‘Breast Cancer Research’ – volume 10, issue 2, page 93

Research Glossary

Definitions for some of the most commonly used research terms are given below. If you cannot find what you are looking for here, a more extensive research glossary can be found at:

The Cochrane Collaboration www.cochrane.org/resources/glossary.htm

Alphabetical search

Click on a particular letter below to go directly to glossory topics beginning with that letter:



Brief summary of a study and its results

Active control
An existing, standard treatment against which an experimental treatment is compared in some types of clinical trials

Adverse event
An undesirable change that occurs during or after medical treatment, but is not necessarily caused by the treatment

Adverse effect
An undesirable change that occurs during or after medical treatment and is caused by the treatment. Commonly called a side effect

See case study


Concealing which treatment a person is given during a trial, to minimise bias or the influence of expectation. Trials can be single blind trial, double blind trial or triple blind trial. Also called ‘masking’


Case-control study
A type of observational study often used to indentify risk factors for disease. People with a specific disease (cases) are compared with people who do not have the disease (controls) and any differences in their characteristics are identified. Alternatively the ‘cases’ can be people who have been exposed to a suspected risk factor, while the ‘controls’ have not e.g. comparing people who have been exposed to organophosphates, with those who haven’t. Case-control studies are usually retrospective study i.e. looking back in time

Case history
See case study

Case report
See case study

Case series
An observational study about a group of similar patients or ‘cases’ e.g. receiving the same medical treatment or having the same disease

Case study
A report detailing observations about a single patient or ‘case’. Also called ‘anecdote’, ‘case history’ or ‘case report’

Clinical trials
A study in which a medical intervention is tested on patients under rigorously controlled conditions. Also called ‘controlled clinical trial’ or ‘clinical study’

Cohort study
An observational study which follows a defined group of people (the cohort) over time to assess the effect of a medical treatment or exposure to a suspected risk factor e.g. asbestos. A prospective cohort study follows the group into the future; a retrospective cohort study uses data that has already been recorded about the group, from a point in the past up to the present day

Control group
Provides a basis for comparison within a trial; results seen in those given the treatment being assessed (experimental group) are compared with results seen in the control group. Control groups vary e.g. they may be given an inactive ‘dummy’ treatment (placebo) or an established treatment which is already in use (active control)

Cross-over trial
A study in which the experimental group and control group are switched during the course of the trial i.e. at the beginning of the trial group A receives the experimental treatment and group B the control treatment, then at a certain point they swap over so that group A is given the control treatment and group B the experimental treatment


Double blind trial
A study in which neither the patients receiving the treatment nor the researchers conducting the trial know which treatment is being given to each patient


Experimental group
The group within a trial which receives the treatment being assessed

Experimental treatment
The treatment being assessed by the research trial


Feasibility study
See pilot study

Focus group
A type of qualitative research in which questions are put to a group of people to find out their opinions about a certain subject. Interview sessions are interactive with open discussion within the group


Gold standard
The best method or treatment currently available, against which new interventions should be compared




Treatment, procedure or therapy

In vitro study
Research done in a controlled environment outside the body (the laboratory) which may involve the use of living cells or tissues, but not the whole living body

In vivo study
Research which tests a medical treatment or procedure on the whole living body (i.e. patients). Also called clinical trial.





Longitudinal study
A study that follows a group of people over a period of time


A statistical technique used to analyse the combined results of multiple studies to generate a more meaningful overall result


Non-experimental study
See observational study

Non-specific effects
Positive effects seen after medical treatment which are caused by the experience of being given a treatment, rather than by direct action of the treatment itself e.g. feeling better due to a reassuring consultation with a practitioner, rather than due to the medicine they prescribed. The placebo effect is one example of a non-specific effect


Observational study
Investigators observe and record what happens to a group of people without influencing the course of events. Also called non-experimental study

Open label trial
A study in which both the patients and investigators know what treatment is being given to each patient


A number from zero to one which describes the likelihood (or probability) that a result could have occurred by chance

Peer review
The process by which articles are selected for publication in academic journals. Studies are assessed by a panel of independent experts in the same field (referees) who decide whether they are suitable for publication. Also known as refereeing

Pilot study
A small initial study conducted to determine whether a larger research study is justified and, if so, how it should be carried out. Also called feasibility study

An inactive ‘dummy’ medicine or treatment. In clinical trials, a placebo that is indistinguishable in appearance from the medical intervention being tested may be given to a control group for purposes of comparison

Placebo effect
A positive change seen after medical treatment which is caused solely by the patient’s psychological response to being given the treatment e.g. improvement occurs because the patient expects to get better. The placebo effect is an example of a non-specific effect.

Pragmatic trial
A study designed to test how effective a medical treatment is when given under ‘real life’ clinical conditions, as opposed to artificially controlled ‘ideal’ conditions

Prospective study
A study in which patients are recruited then studied over a period of time into the future

Publication bias
The tendency for studies with a positive result to be published more readily than those which are negative or inconclusive. Also called reporting bias


Qualitative research
Studies in which unstructured techniques are used to explore broad concepts such as people’s attitudes, experiences and behaviour, without generating numerical results. Commonly used methods include individual in-depth interviews, focus groups, questionnaires and case studies. Relatively small numbers of participants are usually involved

Quantitative research
Studies which involve counting, measuring and the use of statistical mathematics to generate numerical results. Large numbers of participants are needed to produce statistically significant results

Quasi randomised trial
A study in which patients are allocated to the different test groups by a process which is not strictly random e.g. allocation by date of birth, or the order in which they joined the study (known as alternation)


Randomised clinical trial
See randomised controlled trial

Randomised controlled trial (RCT)
A study in which patients are randomly allocated to receive the experimental treatment or be in a comparison group. Also called randomised clinical trial. Considered by some researchers to be the ‘gold standard’ of research methods for determining whether a treatment is effective

Reporting bias
See publication bias

Retrospective study
A study looking back in time at events which have already taken place, using information from case notes, medical records or previous studies


Selection bias
Distortion of the results of a clinical trial due to the method used to decide which patients were given the experimental treatment. Can also mean distortion of the results of a systematic review due to the method used to select which studies were included in the review

Side effect
Any unintentional change caused by a medical treatment, whether undesirable (an adverse effect) or desirable (e.g. improvement of a symptom which the intervention was not intended to treat)

Single blind trial
A study in which either the patients receiving the treatment or the researchers conducting the trial do not know which treatment is being given to each patient

Specific effects
Changes seen after medical treatment which are caused by the action of the treatment itself (e.g. a medicine) rather than the experience of being given the treatment. The opposite of non-specific effects

Statistical significance
The likelihood that a result is due to something other than chance alone i.e. that it is a ‘real’ result

Systematic review
A summary of the total research evidence available on a particular subject, designed to provide more accurate information than single studies. Specific methods are used to search academic journals and identify which studies are suitable for inclusion in the review (e.g. those of suitably high quality). A meta-analysis may or may not be used to statistically analyse pooled results from all the included studies.


Triple blind trial
A study in which the people analysing the data collected during the trial (as well as the patients and researchers) do not know which treatment was given to each patient