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Glossary of Terms




Change (see Theory of Change)


Dyad - Two people engaged in an ongoing relationship. For example parent-child dyad.


Fidelity (see Treatment Fidelity)


Intent to Treat Analysis (ITT) - An assessment of the people taking part in a trial, based on the group they were initially (and randomly) allocated to. This is regardless of whether or not they dropped out, fully adhered to the treatment or switched to an alternative treatment. ITT analyses are often used to assess clinical effectiveness because they mirror actual practice, when not everyone adheres to the treatment, and the treatment people have may be changed according to how their condition responds to it. Studies of drug treatments often use a modified ITT analysis, which includes only the people who have taken at least 1 dose of a study drug. (NICE)




Logic Model - The program logic model is defined as a picture of how your organization does its work – the theory and assumptions underlying the program. A program logic model links outcomes (both short- and long-term) with program activities/processes and the theoretical assumptions/principles of the program. (W.K. Kellogg Foundation Logic Model Development Guide 2006).






Quasi-experimental Study/Design. (QED) - A study based on a true experimental design meets 2 criteria: manipulation of a variable factor between 2 or more groups, and random assignment of patients to those groups. A quasi-experimental study uses the first criterion but patients are not randomly assigned to groups. This means a researcher cannot draw conclusions about 'cause and effect'. This design is frequently used when it is not feasible, or not ethical, to conduct a randomised controlled trial. See also Experimental study. (NICE).


Randomised controlled trial (RCT) - A study in which a number of similar people are randomly assigned to 2 (or more) groups to test a specific drug, treatment or other intervention. One group (the experimental group) has the intervention being tested, the other (the comparison or control group) has an alternative intervention, a dummy intervention (placebo) or no intervention at all. The groups are followed up to see how effective the experimental intervention was. Outcomes are measured at specific times and any difference in response between the groups is assessed statistically. This method is also used to reduce bias. (NICE).




Theory of Change (ToC) - “ToCs articulate the change process within interventions and describe the sequence of events linking intervention activities to their long-term outcomes. They make explicit the conditions and assumptions required to enable change and acknowledge the role of context in influencing the process. Diagrams are often used to depict a ToC as most complex interventions consist of elements interacting in a non-linear fashion, with indirect causal pathways and feedback loops. This is in contrast to logic models and logical frameworks, which tend to be more rigid and linear in outlining the inputs, processes, outputs and outcomes of an intervention. (Maini R, Mounier-Jack S, Borghi J How to and how not to develop a theory of change to evaluate a complex intervention: reflections on an experience in the Democratic Republic of Congo BMJ Global Health 2018” see also, Connell JP Weiss C . Nothing as practical as good theory: exploring theory-based evaluation for comprehensive community initiatives for children and families. In. Connell JP , ed. New approaches to evaluating community initiatives: concepts, methods, and contexts. Washington, DC: Aspen Institute, 1995:65–92)

Treatment Fidelity - In intervention research, treatment fidelity is defined as the strategies that monitor and enhance the accuracy and consistency of an intervention to ensure it is implemented as planned and that each component is delivered in a comparable manner to all study participants over time. (Smith, Stephen W.; Daunic, Ann P.; Taylor, Gregory G. Education and Treatment of Children, v30 n4 p121-134 Nov 2007).