Table 2 Rigour techniques for qualitative research

Sampling adequacy

This refers to obtaining an appropriate sample for the research topic

To ensure an appropriate sample was obtained, we sought data saturation (i.e., prominent, recurring patters across multiple studies that are relevant to the research question). To avoid falsely achieving saturation, we purposely gathered a heterogeneous sample of the literature that was conceptually rich and depicted the scale-up process in-depth. To increase our likelihood of correctly achieving saturation; we aimed to be inclusive of all potentially relevant studies that may inform this critical synthesis.

Triangulation

This refers to cross-comparing multiple sources to verify the content within, and aid in developing a rich understanding

We retrieved all available literature relevant to the scale-up process for each Population Health Intervention, including empirical studies, reports, commentaries, webpages, and presentations from peer-reviewed and grey literature.

Active analytic stance

This refers to collecting and analyzing data concurrently, to help the researcher better identify what is known and what needs to be examined further

As we began data collection and our concurrent analyses, we became more familiar with the data and gained greater insight into the meaning of the data. We compared new data with existing data to examine whether they supported or refuted our existing themes - this approach helped inform our future data collection. As this process progressed, we noticed that themes became repetitive, providing evidence of verification and completeness of the results.