Axial coding¹: second level of coding in a grounded theory study that involves categorising, recategorising, and condensing first level codes by connecting categories and subcategories.

Blinding (masking): in an experimental study, refers to whether patients, clinicians providing an intervention, people assessing outcomes, and/or statisticians were aware or unaware of the group to which patients were assigned. In the design section of Evidence-Based Nursing abstracts of treatment studies, the study will be identified as blinded, with specification of who was blinded; unblinded, if all parties were aware of patients' group assignments; or blinded (unclear) if the authors did not report or provide us with an indication of who was aware or unaware of patients' group assignments.

Concealment of randomisation: concealment of randomisation is specified in the design section of Evidence-Based Nursing abstracts of treatment studies as follows: allocation concealed (deemed to have taken adequate measures to conceal allocation to study group assignments from those responsible for assessing patients for entry in the trial [ie, central randomisation; numbered, opaque, sealed envelopes; sealed envelopes from a closed bag; numbered or coded bottles or containers; drugs prepared by the pharmacy; or other descriptions that contain elements convincing of concealment]); allocation not concealed (deemed to have not taken adequate measures to conceal allocation to study group assignments from those responsible for assessing patients for entry in the trial [ie, no concealment procedure was undertaken, sealed envelopes that were not opaque, or other descriptions that contained elements not convincing of concealment]); unclear allocation concealment (the authors did not report or provide a description of an allocation concealment approach that allowed for the classification as concealed or not concealed).

Concept map (schematic model)¹: representation of concepts in a figure, using boxes, arrows, and other symbols.

Confidence interval (CI): quantifies the uncertainty in measurement; usually reported as 95% CI, which is the range of values within which we can be 95% sure that the true value for the whole population lies.

Diagnostic (gold or criterion) standard: the current best available measure of an outcome; used for assessing properties of a new diagnostic or screening test. The results from a new test are compared with the results from the diagnostic standard to assess the usefulness of the new test (ie, its sensitivity, specificity, and likelihood ratios).

Giorgi's method²: an approach to the analysis of phenomenological data that involves 4 steps: (1) reading the text to get a sense of the whole; (2) dividing the text into meaning units; (3) transforming the language of the participants into disciplinary language (eg, nursing); and (4) synthesising the structure to describe its essence.

Grounded theory¹: an approach to collecting and analysing qualitative data with the aim of developing theories grounded in real world observations.

Intention to treat analysis (ITT): all patients are analysed in the groups to which they were randomised, even if they failed to complete the intervention or received the wrong intervention.

Likelihood ratio (for positive and negative results)³: a way of summarising the findings of a study of a diagnostic test for use in clinical situations where there may be differences in the prevalence of the disease. The likelihood ratio for a positive test is the likelihood that a positive test result comes from a person that really does have the disorder rather than one that does not have the disorder (sensitivity/1-specificity). The likelihood ratio for a negative test is the likelihood that a negative test result comes from a person with the disorder rather than one without the disorder (1-sensitivity/specificity).

Linear analysis (regression): a statistical technique for determining the relation (prediction equation) between 2 continuous variables.

Multivariate analysis⁴: analysis involving multiple independent or dependent variables.

Number needed to treat (NNT): number of patients who need to be treated to prevent 1 additional negative event (or to promote 1 additional positive event); this is calculated as 1/absolute risk reduction (rounded to the next whole number), accompanied by the 95% confidence interval.

Odds ratio (OR): describes the odds of a patient in the experimental group having an event divided by the odds of a patient in the control group having the event or the odds that a patient was exposed to a given risk factor divided by the odds that a control patient was exposed to the risk factor.

Open coding¹: first level of coding in a grounded theory study, consisting of basic descriptive coding of narrative content.

Phenomenology¹: an approach to inquiry that emphasises the complexity of human experience and the need to understand that experience holistically as it is actually lived.

Quasi-randomised study: participants are not randomly allocated to groups, but some other form of allocation is used (eg, day of the week, month of birth).

Relative benefit increase (RBI): the proportional increase in the rates of good events between experimental and control participants; reported as a percentage (%).

Relative risk (RR): risk of adverse effects with a treatment relative to risk for those who do not receive treatment.

Relative risk reduction (RRR): the proportional reduction in outcome rates of bad events between experimental and control participants; it is reported as a percentage (%).

Sensitivity⁵: a measure of a diagnostic test's ability to correctly detect a disorder when it is present in a sample of people.

Specificity⁵: a measure of a diagnostic test's ability to correctly identify the absence of a disorder in a sample of people who do not have the disorder.

Stratified randomisation⁶: used in trials to ensure that equal numbers of participants with a particular characteristic (eg, age) are allocated to each comparison group.

Weighted: statistical analysis accounts for differences in certain important variables.