How to Elicit Explainability Requirements? A Comparison of Interviews, Focus Groups, and Surveys

TL;DR

This study compares interviews, focus groups, and surveys for eliciting explainability requirements in software, finding that a hybrid approach optimizes efficiency and coverage, with taxonomy use enhancing the process.

Contribution

It provides an empirical comparison of three elicitation methods and offers practical recommendations for combining surveys and interviews with taxonomy integration.

Findings

Interviews are most efficient per participant and time.

Surveys gather the most needs but with high redundancy.

Delayed taxonomy introduction increases need diversity.

Abstract

As software systems grow increasingly complex, explainability has become a crucial non-functional requirement for transparency, user trust, and regulatory compliance. Eliciting explainability requirements is challenging, as different methods capture varying levels of detail and structure. This study examines the efficiency and effectiveness of three commonly used elicitation methods - focus groups, interviews, and online surveys - while also assessing the role of taxonomy usage in structuring and improving the elicitation process. We conducted a case study at a large German IT consulting company, utilizing a web-based personnel management software. A total of two focus groups, 18 interviews, and an online survey with 188 participants were analyzed. The results show that interviews were the most efficient, capturing the highest number of distinct needs per participant per time spent. Surveys collected the most explanation needs overall but had high redundancy. Delayed taxonomy introduction resulted in a greater number and diversity of needs, suggesting that a two-phase approach is beneficial. Based on our findings, we recommend a hybrid approach combining surveys and interviews to balance efficiency and coverage. Future research should explore how automation can support elicitation and how taxonomies can be better integrated into different methods.