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**Absolute benefit increase (ABI):** the absolute arithmetic difference in events rates.

**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.

**Data saturation (saturation, redundancy)**^{1}**:** process of collecting data in a qualitative research study to the point where no new themes are generated.

**Ethnography (ethnographic study)**^{1}**:** an approach to inquiry that focuses on the culture or subculture of a group of people, with an effort to understand the world view of those under study.

**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.

**Hermeneutic phenomenology**^{1}**:** the study of the methodological principles of interpretation by using narrative texts to explain a phenomenon.

**Heterogeneity**^{2}**:** the degree to which the effect estimates of individual studies in a meta-analysis differ significantly.

**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).

**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.

**Participatory action research:** action oriented research in which the researchers and participants are partners in developing the question, intervention, and evaluation.

**Power**^{4}**:** the ability of a study to detect an actual effect or difference between groups; it has to do with the adequacy of sample size. Before a study begins, researchers often calculate the number of participants required to detect a difference between 2 groups. If a study has insufficient power (ie, sample size is too small), actual differences between groups may not be detected.

**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).

**Random effects model**^{2}**:** gives a summary estimate of the magnitude of effect in meta-analysis. It takes into account both within-study and between-study variance and gives a wider confidence interval to the estimate than a fixed effects model if there is significant between-study variation.

**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 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).

**Triangulation**^{1}**:** use of multiple methods or perspectives to collect and interpret data about some phenomenon, to converge on an accurate representation of reality.

**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.

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**Absolute benefit increase (ABI):** the absolute arithmetic difference in events rates.

**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.

**Data saturation (saturation, redundancy)**^{1}**:** process of collecting data in a qualitative research study to the point where no new themes are generated.

**Ethnography (ethnographic study)**^{1}**:** an approach to inquiry that focuses on the culture or subculture of a group of people, with an effort to understand the world view of those under study.

**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.

**Hermeneutic phenomenology**^{1}**:** the study of the methodological principles of interpretation by using narrative texts to explain a phenomenon.

**Heterogeneity**^{2}**:** the degree to which the effect estimates of individual studies in a meta-analysis differ significantly.

**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).

**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.

**Participatory action research:** action oriented research in which the researchers and participants are partners in developing the question, intervention, and evaluation.

**Power**^{4}**:** the ability of a study to detect an actual effect or difference between groups; it has to do with the adequacy of sample size. Before a study begins, researchers often calculate the number of participants required to detect a difference between 2 groups. If a study has insufficient power (ie, sample size is too small), actual differences between groups may not be detected.

**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).

**Random effects model**^{2}**:** gives a summary estimate of the magnitude of effect in meta-analysis. It takes into account both within-study and between-study variance and gives a wider confidence interval to the estimate than a fixed effects model if there is significant between-study variation.

**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 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).

**Triangulation**^{1}**:** use of multiple methods or perspectives to collect and interpret data about some phenomenon, to converge on an accurate representation of reality.

**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.

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