Nomenclature follows the standard international nomenclature
for meridians; an alphabetic code agreed at a meeting of the WHO Scientific
Group in 1989.
Bias
Deviation of results from the truth or mechanisms leading to
such deviation (e.g. analysis bias, measurement bias, publication
bias, selection bias, withdrawal bias and others). In clinical studies,
bias is mainly controlled by blinding and randomisation.
Blinding
Study participants and/or study staff (therapists, outcome assessors)
are unaware of who receives the experimental or control treatment.
Cohort
A group of individuals with some characteristics in common who
are followed over time to see who develops a disease or outcome, and
factors associated with this.
Complementary and alternative medicine
Includes all such practices and ideas which are outside the domain
of conventional medicine in several countries and defined by its users
as preventing or treating illness, or promoting health and well-being.
These practices complement mainstream medicine by (1) contributing
to a common whole; (2) satisfying a demand not met by conventional
practices; and (3) diversifying the conceptual framework of medicine.
(CAM definition adopted by the Cochrane Complementary Medicine Field)
Confidence interval
Quantifies the uncertainty in measurement. Usually reported as
95% CI, which is the range of values within which one can expect to
find the true value in 95% of cases.
Controlled trial
Control is a standard against which experimental observations
may be evaluated. In clinical trials, one group of participants is
given an experimental intervention, while another group (i.e. the
control group) is given either a standard treatment for the disease,
a placebo or no treatment at all.
Crossover
Participants in the intervention group receive the control treatment
upon completion of the treatment cycle. Similarly those in the control
group ‘crossover’ and receive the experimental intervention.
Double-blind trial
A clinical trial design in which neither the participating individuals
nor the study staff know which participants are receiving the experimental
treatment and which are receiving the control treatment or placebo.
Double-blind trials are thought to produce objective results, since
the expectations of the participants and study staff about the experimental
drug do not affect the outcome.
Intention-to-treat analysis
Data are analysed according to original intervention assignment
of participants, whether or not they complete/receive treatment.
Meta-analysis
A quantitative statistical method to pool trial data in a single
estimate. Can be part of a systematic review.
Number needed to treat
Number of patients who need to be treated to prevent one additional
negative event (or to promote one additional positive event).
Odds ratio
Ratio of probability of an event in one group to probability
of the event in a compared group.
Power
The ability to detect a clinically important difference if one
exists. Power of a study increases with larger sample sizes and more
precise measurement.
P-value
Probability that an observed difference between groups occurred
by chance alone. A result is conventionally regarded as ‘statistically
significant’ if the likelihood that it is due to chance alone is less
than five times out of 100 (P<0.05).
Randomisation
The process by which patients in a clinical trial are randomly
assigned to experimental intervention or control treatment. Randomisation
minimises the differences among groups by equally distributing participants
with particular characteristics (known or unknown) among all the trial
arms.
Randomised clinical trial
Prospective study where participants are randomly allocated to
receive experimental or control treatment.
Relative risk
Proportion of patients experiencing an outcome in the treated
group divided by the proportion experiencing the outcome in the control
group.
Standard deviation
A statistical measure of the distance a quantity is likely to
lie from its average value (i.e. a measure of dispersion). The more
widely the scores are spread out, the greater the standard deviation.
Standardised mean difference
In a systematic review, a way of combining the results of studies
that may have measured the same outcome (e.g. pain) in different ways,
using different scales. Effects are expressed as standard values with
no units.
Systematic review
Review in which literature from multiple sources is systematically
searched for, assessed and evaluated to answer clearly formulated
questions.
