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Glossary of terms

of pain. In health care, qualitative techniques have been commonly used
in research documenting the experience of chronic illness and in studies
about the functioning of organisations. Qualitative research techniques such
as focus groups and in-depth interviews have been used in one-off projects
commissioned by guideline development groups to find out more about the
views and experiences of patients and carers.
Quality-adjusted life years A measure of health outcome which looks at both length of life and quality of life.
(QALYs) QALYs are calculated by estimating the years of life remaining for a patient
following a particular care pathway and weighting each year with a quality of
life score (on a 0 to 1 scale). 1 QALY is equal to 1 year of life in perfect health,
or 2 years at 50% health, and so on.
Quantitative research Research that generates numerical data or data that can be converted into
numbers, for example clinical trials or the national Census that counts people
and households.
Quasi-random allocation A method of assigning or allocating participants in an experimental study
whereby the assignment of patients to treatment and comparison groups is not
done randomly, or patients are not given equal probabilities of selection. For
example, participants may be assigned to the groups based on their date of birth
or day of the week or every alternate person. These methods lead to selection
bias in a study. See also random allocation.
Random allocation A method that uses the play of chance to assign participants or units to
comparison groups in an experimental study, for example by using a random
numbers table or a computer-generated random sequence. Random allocation
implies that each individual (or each unit in the case of cluster randomisation)
being entered into a study has the same chance of receiving each of the possible
interventions. See also quasi-random allocation.
Randomisation The process of randomly allocating participants into comparison groups in a
controlled trial. The aim of this process is to ensure that the experimental and
the control groups are similar with respect to all potential confounding variables
except the treatment or intervention being investigated.
Randomised controlled trial An experimental study to test a specific drug or other treatment in which people are
(RCT) randomly allocated to two (or more) groups: one (the intervention or
experimental group) receiving the treatment that is being tested, and the other
(the comparison or control group) receiving an alternative treatment, a placebo
(dummy treatment) or no treatment. The two groups are followed up to compare
differences in outcomes to see how effective the experimental treatment was.
Receiver operating A curve representing the relationship between sensitivity (true positive fraction
characteristic curve and 1 − specificity (false positive fraction) in the case of a continous test result. It
(ROC curve) displays the trade-offs between sensitivity and specificity when the cut-off value
for a positive test result is varied. The measure used to determine the overall
accuracy of a test using the ROC curve is known as the area under ROC curve
(AROC). In general, an AROC of 0.5–0.7 is associated with a marginally useful
test, of 0.7–0.9 with a good test, and of greater than 0.9 with an excellent test.
Red flag symptoms and signs Important symptoms or signs of dehydration whose presence is associated with
a risk of progression to shock.
Remote assessment An assessment carried out when the patient is geographically remote from the
assessor (e.g. via telephone) such that physical examination is not possible.
Regression analysis A statistical technique used to predict the effect or influence of one or more
independent factors/variables on a dependent factor/variable, for example the
effect of age, smoking and occupation on the incidence of lung cancer. Logistic
regression and meta-regression are two types of regression analysis.
Relative risk or risk ratio The ratio of the risks of a given event or outcome (e.g. an adverse reaction to the
(RR) drug being tested) in one group of subjects compared with another group. When
the ‘risk’ of the event is the same in the two groups, the relative risk is 1. In a
study comparing two treatments, a relative risk of 2 would indicate that patients
receiving one of the treatments had twice the risk of an undesirable outcome
than those receiving the other treatment.

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