Does this intervention work? Fidelity measurement in a preschool-based vocabulary intervention
Background: Fidelity refers to whether an intervention is delivered as intended. Without understanding fidelity, we can’t know whether an intervention truly works. This requires careful measurement of how an intervention is delivered, which is challenging when studies are conducted in real-world settings.
Aim: This presentation will explain the concept of intervention fidelity, why it is important, and how it is measured. A study will be presented as an example of how fidelity can be measured. Here, the intervention is a teacher-led, shared-reading vocabulary intervention for preschool-aged children in Iceland. The relationship between implementation fidelity and children’s outcomes will be discussed.
Method/approach: Five preschools participated in the intervention (62 children, 11 teachers). Dose was measured by session attendance, session length, and exposure to target words during sessions. Adherence was the number of required elements delivered in each session. Quality was how well teachers’ actions aligned with the intent of the intervention. Responsiveness was children’s engagement. Children’s language was assessed with a general language test and intervention-specific vocabulary probes before and after the intervention. Ethical approval was obtained from Visindasiðanefnd.
Results/findings: On average children attended 80.2% of the lessons, received 342 minutes of intervention, and were exposed to target words 778 times (dose). Teachers’ self-reported adherence was 91.3%, but only 56.5% when measured from recordings. The mean quality and responsiveness were both 3.9 out of 5. All aspects of fidelity were highly correlated. Responsiveness was most closely linked to children’s language outcomes.
Conclusion: The findings highlight the complexity of measuring and interpreting fidelity in interventions conducted in real-world settings and high variations in children’s individual experiences of fidelity.
Implications for children and families: This paper explains why it is important to monitor how interventions are implemented in preschools and how this can help ensure that preschool interventions are evidence-based.
Implications for practitioners: This paper explains the construct of fidelity and how it relates to understanding research evidence and effectively transferring it to classroom practice.
Funding: Menntarannsóknasjóður [219261-051].
Keywords: multilingual, preschool, pedagogy, language, fidelity
This presentation relates to the following United Nations Sustainable Development Goals: