Cochrane Style Manual 2.0
Common terms and terminology

Some terms and phrases are commonly used in Cochrane documents. The way in which these should be presented is shown below. See also Names specific to Cochrane.

Correct usage

Incorrect usage

care giver or caregiver (be consistent)


Chi2 statistic

Chi2 test

Chi-squared test or statistic

Chi-square test or statistic

χ2 statistic

cluster-randomized trialcluster randomized trial
controlled before-after studiescontrolled before after studies

cross-over study/trial

cross over study/trial or crossover study/trial


Note: also single-blind, triple-blind

double blind

Note: also single blind, triple blind


Note: the verb form is 'drop out’ without hyphenation


drop out


Note: at start of sentence use 'E-learning'


e learning

end point or endpoint

Note: 'time point' should be written as two separate words (see below)


evidence base



evidence based

false negative, false positive, true negative, true positive (when used as nouns)

e.g. the result was a false positive

false-positive, false-negative, true-negative, true-positive (when used as adjectives)

e.g. a false-positive result


fixed-effect model

Note: compared with random-effects model

Note: there is also a fixed-effects model (i.e. when the pool of studies is assumed to be fixed and only provides an estimate of the average of the effects of just these studies, without aiming at generalization to future studies), but this would rarely be appropriate for a Cochrane review. If used it should be clearly indicated to avoid being changed to fixed-effect model.

fixed effect model
fixed-effects model





follow up (verb) or follow-up (adjective or noun)

e.g. 'Seven participants were followed up for 10 days.' (verb)

e.g. 'The follow-up period was 10 weeks.' (adjective)

e.g. 'The follow-up was shorter than expected.' (noun)

forest plot

forrest plot


More recently, GRADE assessments refer to ‘certainty’, rather than ‘quality’. Use the terminology consistent with the GRADE guidance of software you are using, and in summary of findings tables, use the corresponding wording for the grades of evidence (see below).

For certainty:

GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect.
Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.
Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect.
Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.

For quality:

GRADE Working Group grades of evidence
High quality: further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: we are very uncertain about the estimate.

Note: for further information, see The GRADE Working Group clarifies the construct of certainty of evidence.

See also: Handbook version 6, chapter 14.

'Gram' should be capitalized and not hyphenated when used as Gram stain; gram negative and gram positive should be lowercase and only hyphenated when used as a unit modifier.

e.g. Gram staining

e.g. the bacteria were gram negative

e.g. gram-positive and gram-negative bacteria

Gram-positive and Gram-negative bacteria

gram positive and gram negative bacteria

gram staining showed ...


e.g. We handsearched three journals.

e.g. The handsearching process ...

hand search

hand washing

Note: present as two words unless being used to modify a noun.

e.g. The studies investigated hand washing for prevention of infections.

e.g. The studies investigated hand-washing promotion for prevention of infections.

The studies investigated handwashing.

The studies investigated hand-washing.

The studies investigated handwashing promotion.

The studies investigated hand washing promotion.

health care (noun) or healthcare (adjective)

e.g. healthcare professionals (adjective)

e.g. important aspect of health care (noun)

I2 statistic

I-squared statistic
I-square statistic
I2 test

intention-to-treat analysis

intention to treat analysis



low-income, middle-income, and high-income countries

Note: see the classifications of all countries according to their economies on the World Bank website

developing countries
developed countries

multiple-drug resistance
multiple-drug resistant

multidrug resistance
multidrug resistant

number needed to treat for an additional beneficial outcome


number needed to treat to benefit

number needed to treat for an additional harmful outcome


number needed to treat to harm


on line

open-labelopen label

participant or person; participants or people

Note: use participant (for people participating in any trials/studies mentioned in the review) or person instead of subject or patient, unless it changes the meaning of the text (e.g. people with ulcers rather than patients with ulcers). If trials are exclusively concerned with a single population such as children or women, use children or women instead of participants.


per cent

Note: see also Guidance on usage and presentation of commonly used symbols


PICO: broadly speaking, PICO stands for 'population, intervention(s), comparison(s) and outcomes', but there is no standard definition. For example, the 'P' can stand for 'participants', 'population' or 'problem', and the 'C' for 'control', 'comparator' or 'comparison(s)'.   




pre-operative or pre operative

peri-operative or peri operative

post-operative or post operative


low-quality (adjective)

moderate-quality (adjective)

high-quality  (adjective)

e.g. high-quality evidence


low quality (adjective)

moderate quality (adjective)

high quality  (adjective)

random-effects model

random effects model
random-effect model



risk of bias

e.g. We assessed the risk of bias in the included studies using RoB 2.

e.g. We assessed the risk of bias in the included studies using RoB 1.

risk of bias assessment

risk of bias table

Note: For more about the names of Cochrane risk of bias tools, see Names specific to Cochrane.

‘risk of bias’

Risk of bias

risk-of-bias assessment

Risk of Bias Table

short-term or long-term (adjective)

e.g. short-term follow-up was three months

short term or long term (noun)

e.g. outcomes that occurred in the short term


summary of findings table

summary-of-findings table

Summary of findings table

'summary of findings’ table

SoF table


sub group

Tau2 statistic
Tau2 test

text word


time point



time-to-event analysis/data

time to event analysis/data

wait list or wait-list control (US English)

waiting list or waiting-list control (UK English)

waitlist, wait list control

waiting-list, waiting list control


web site


well being


white (adjective)

e.g. The white participants …

See also: ethnic group names

white (noun)

World Wide Web

world wide web


Section info
Elizabeth Royle (
Describe change
Further updates to clarify guidance on risk of bias
Some items on this page moved to the section on Names.
Change date
22 April 2021