The evaluation concept follows a comprehensive mixed-methods approach. It includes a summative evaluation of intervention effectiveness, formative evaluations at the process and system levels, and a health economic analysis.

Within this framework, the University of Potsdam is responsible for the formative process-level evaluation. The aim is to assess how well the program is implemented in practice, which factors promote or hinder its implementation, and how implementation quality affects program success.

Key research questions include:

• What conditions facilitate or hinder the implementation of fruehstArt?
• How is the quality of implementation perceived by participants – and do these perceptions differ between families?
• To what extent does implementation quality influence the program’s effectiveness?

To answer these questions, semi-structured interviews are conducted with parents of participating children as well as with healthcare providers (coaches and pediatricians) involved in the project. A sample of 15–20 parents and around 20 providers is targeted.

In addition, an Implementation Index—covering key dimensions such as dose, adherence, implementation quality, and responsiveness (based on Dowling & Barry, 2021)—will be developed. Data are collected via inputs from coaches and parents in the web application (eHealth platform), as well as from questionnaires administered at T1 and T2 in the summative evaluation. The Implementation Index will be analyzed both independently and in combination with the summative evaluation data (via ID linkage), to assess whether stronger implementation correlates with better outcomes.