My knowledge on samples and sampling to address my research question and design

In contemplating the selection of participants for my Delphi questionnaire, I find myself deliberating between purposive sampling and snowball sampling. While both approaches offer distinct advantages and considerations, my inclination leans towards purposive sampling for several reasons.

My familiarity with HIV-related organisations instils confidence in my ability to identify participants who possess the required professional experience and knowledge essential for the study. Purposive sampling enables me to identify individuals with heterogeneous characteristics while ensuring they align with the study's objectives. According to the author, a Delphi methodology does not focus on the number of incidences in the sampling frame and it does not require a large sample that is representative of any population. This is because it is a mechanism to reach a group consensus and the purpose is to collect data high in quality that allows a detailed exploration and understanding of a specific topic (Keeley et al., 2016). Therefore, this method enables me to use greater judgement of the participants that I select and I am able to minimise homogeneity that could potentially compromise the range and depth of insights generated (Naisola-Ruiter, 2022).

Furthermore, I have reservations regarding snowball sampling's tendency to identify participants who may be too similar to the characteristics of the initial recruits. Diversity is critical in fostering comprehensive consensus within the Delphi process, and purposive sampling offers a more structured approach to achieving this diversity without relying on participants to recruit others. I am also weary of burdening participants with additional tasks that compete with the efficiency of the study, and this can alleviated by the deliberate selection allowed through purposive sampling.

In the literature that I’ve come across, there is a preference for expert or purposive sampling in Delphi studies. Keeley et al. (2016) advocate for purposive sampling's efficacy in assembling heterogeneous maximum variation samples, a principle that aligns with my aim to develop a panel consisting of a spectrum of high and middle-level professionals in Antiretroviral care management and data science (Keeley et al., 2016).

References

Keeley, T., Williamson, P., Callery, P., Jones, L., Mathers, J., Jones, J., Young, B., & Calvert, M. (2016). The use of qualitative methods to inform Delphi surveys in core outcome set development. Trials, 17, 1-9.

Naisola-Ruiter, V. (2022). The Delphi technique: a tutorial. Research in Hospitality Management, 12(1), 91–97-91–97.