Development of a sampling matrix and topic guide for qualitative in-depth interviews exploring the landscape of child protection in dentistry

Objectives: To devise an appropriate sampling matrix and topic guide for exploratory in-depth interviews with members of the dental team in Scotland, in order to map the landscape of child protection in dentistry.
Methods: A purposive sampling matrix was selected to give a heterogeneous/ broad cross section of members of the dental team to allow comparative understanding. The target population included dental practitioners, dental nurses and dental hygienists/therapists working in dental primary care in Scotland.
The topic guide for in-depth exploratory interviews was developed using a “bottom up” approach. All topics of interest were listed then sorted under main and sub topic headings.
Results: Fifteen initial purposive selection criteria were identified and refined to 12 primary and 3 secondary criteria. Primary criteria were entered into a sampling matrix table to give a sample size of 18 to 50 participants which is in keeping with average participant numbers in qualitative research.
Topic guide development resulted in 8 main headings to explore the research question of “What is involved in the decision by a member of the dental team to refer a paediatric patient or not, and what influences the decision?” Each main heading was followed by between 2 to 14 sub topic headings. The topic guide will now be piloted before being learned by the main researcher for use in the final study.
Conclusions: Creating a sampling matrix for this qualitative research project has allowed the consideration of various selection criteria to ensure adequate mapping of the views of dental team members regarding child protection. The construction of a topic guide provides a checklist of essential topics that must be covered during in depth interviews. It provides the ground a researcher wishes to cover but does not dictate the questions to be asked, therefore giving flexibility in the question order and open question wording.