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Blinding (masking):
in an experimental study, refers to whether patients, clinicians providing an intervention, people assessing outcomes, and/or data analysts 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 is 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; sequentially 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 were not sequentially numbered, 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).
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.
Constant comparison:1
a procedure used in qualitative research wherein newly collected data are compared in an ongoing fashion with data obtained earlier, to refine theoretically relevant categories.
Fixed effects model:2
gives a summary estimate of the magnitude of effect in meta-analysis. It takes into account within-study variation but not between-study variation and hence is usually not used if there is significant heterogeneity.
Grounded theory:1
an approach to collecting and analysing qualitative data with the aim of developing theories grounded in real world observations.
Inception cohort:
a defined, representative sample of patients is assembled for a study at a common (ideally early) point in their disease or condition and followed up over time.
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.
Number needed to harm (NNH):3
number of patients who, if they received the experimental treatment, would lead to 1 additional person being harmed compared with patients who receive the control treatment; this is calculated as 1/absolute risk increase (rounded to the next whole number), accompanied by the 95% confidence interval.
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.
Phenomenology:1
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; it is reported as a percentage (%).
Relative risk (RR) (risk ratio):
proportion of patients experiencing an outcome in the treated (or exposed) group divided by the proportion experiencing the outcome in the control (or unexposed) group.
Relative risk increase (RRI):
the proportional increase in bad outcomes between experimental and control participants; it is reported as a percentage (%).
Relative risk reduction (RRR):
the proportional reduction in bad outcomes between experimental and control participants; it is reported as a percentage (%).
Standardised mean difference:2
in a systematic review, a way of combining the results of studies that may have measured the outcome (eg, pain) in different ways, using different scales; effects are expressed as a standard value, with no units (difference between 2 means / estimate of within group standard deviation).
Symbolic interaction:1
a qualitative research method that focuses on the way in which people make sense of social interactions and the meanings they attach to social symbols such as language.
Theoretical sampling:1
in qualitative studies, selection of study participants based on emerging findings to ensure adequate representation of important themes.
Weighted:
statistical analysis accounts for differences in certain important variables.
Weighted mean difference:2
in a meta-analysis, used to combine outcomes measured on continuous scales (eg, height), assuming that all trials measured the outcome on the same scale; the mean, standard deviation and sample size of each group are known, and weight given to each trial is determined by the precision of its estimate of effect.