JMIR Publications

ABSTRACT

Background:

In-depth interviews are a common method of qualitative data collection that allows for gathering rich data on individuals’ perceptions and behaviors that would be challenging to collect with quantitative methods. Researchers typically need to make decisions on sample size a priori. Although studies have assessed when saturation has been achieved, there is no agreement on the minimum number of interviews needed to achieve saturation. Additionally, to date most research on saturation has been based on in-person data collection.

Objective:

This study aimed to identify the number of virtual interviews needed to achieve true code saturation or near code saturation.

Methods:

The analyses for this study were based on data from 5 Food and Drug Administration-funded studies conducted virtually with patients with underlying medical conditions or with healthcare providers who provide primary or specialty care to patients. We extracted code- and interview-specific data and examined the data summaries to determine when true saturation or near saturation was reached.

Results:

The sample size used in the 5 studies ranged from 30 to 70 interviews. True saturation was reached after 91% to 100% of planned interviews, whereas near saturation was reached after 33% to 60% of planned interviews (15-23 interviews). Studies that relied heavily on deductive coding and studies that had a more structured interview guide reached both true saturation and near saturation sooner.

Conclusions:

Our study provides support that near saturation may be a sufficient measure to target and that conducting additional interviews after that point may result in diminishing returns. Factors to consider in determining how many interviews to conduct include the structure and type of questions included in the interview guide, the coding structure, and the population under study. Studies with less structured interview guides, studies that rely heavily on inductive coding and analytic techniques, and studies that include populations that may be less knowledgeable about the topics discussed may require a larger sample size to reach an acceptable level of saturation.