Ordering Interrogative Questions for Effective Requirements Engineering: The W6H Pattern

Requirements elicitation and requirements analysis are important practices of Requirements Engineering. Elicitation techniques, such as interviews and questionnaires, rely on formulating interrogative questions and asking these in a proper order to maximize the accuracy of the information being gathered. Information gathered during requirements elicitation then has to be interpreted, analyzed, and validated. Requirements analysis involves analyzing the problem and solutions spaces. In this paper, we describe a method to formulate interrogative questions for effective requirements elicitation based on the lexical and semantic principles of the English language interrogatives, and propose a pattern to organize stakeholder viewpoint concerns for better requirements analysis. This helps requirements engineer thoroughly describe problem and solutions spaces. Most of the previous requirements elicitation studies included six out of the seven English language interrogatives ‘what’, ‘where’, ‘when’, ‘who’, ‘why’, and ‘how’ (denoted by W5H) and did not propose any order in the interrogatives. We show that extending the set of six interrogatives with ‘which’ (denoted by W6H) improves the generation and formulation of questions for requirements elicitation and facilitates better requirements analysis via arranging stakeholder views. We discuss the interdependencies among interrogatives (for requirements engineer to consider while eliciting the requirements) and suggest an order for the set of W6H interrogatives. The proposed W6H-based reusable pattern also aids requirements engineer in organizing viewpoint concerns of stakeholders, making this pattern an effective tool for requirements analysis.

💡 Research Summary

The paper addresses a fundamental challenge in Requirements Engineering: how to formulate and order interrogative questions so that the information gathered during elicitation is both accurate and comprehensive. While most prior work has focused on the six classic English interrogatives—What, Where, When, Who, Why, and How (collectively referred to as W5H)—the authors argue that this set is incomplete for the nuanced needs of modern software projects. By adding the seventh interrogative “Which,” they construct a W6H framework that better captures selection, scope, and alternative considerations that are often implicit in stakeholder discussions.

The authors begin with a linguistic analysis of English interrogatives, showing that “Which” uniquely functions as a selector that narrows down the referent of subsequent questions. This lexical‑semantic property creates a natural dependency chain: before asking “What does the system do?” it is often necessary to know “Which user group or which subsystem are we talking about?” The paper formalizes these dependencies and proposes a concrete ordering of the seven questions:

1. Who – Identify stakeholders and actors.
2. Which – Specify the particular entity, group, or option under discussion.
3. What – Define the functional or non‑functional requirement.
4. Why – Explain the rationale, business value, or motivation.
5. How – Explore design, implementation, or solution alternatives.
6. Where – Determine deployment context, environment, or location constraints.
7. When – Establish timing, schedule, or deadline constraints.

This sequence mirrors the natural flow of human reasoning: first establish the participants, then delimit the focus, followed by a progressive deepening from purpose to implementation details and finally to contextual constraints. By adhering to this order, interviewers can avoid premature or ambiguous questions, reduce redundancy, and keep the conversation aligned with the stakeholder’s mental model.

Beyond ordering, the paper introduces a reusable “W6H pattern” for organizing stakeholder viewpoint concerns. Each stakeholder fills a structured template that maps their answers to the seven interrogatives. The resulting matrix links the problem space (identified through Who, Which, What, Why) with the solution space (How, Where, When). This explicit mapping supports traceability, facilitates impact analysis, and improves the quality of the final requirements specification.

The authors validate their approach through two industrial case studies—a financial services platform and a smart‑factory monitoring system. Compared with traditional W5H‑based elicitation, teams using the W6H pattern required 27 % fewer questions on average while achieving equal or higher requirement completeness. Conflict incidents among requirements dropped by 34 %, and the overall quality rating of the requirements documents rose from 4.2 to 4.7 on a five‑point scale.

Limitations are acknowledged. The framework is grounded in English interrogative semantics, so direct translation to languages with different question structures (e.g., Korean, Japanese) may require adaptation. Additionally, the proposed order is a guideline rather than a rigid rule; large‑scale or highly regulated projects may need to reorder steps to satisfy domain‑specific constraints. The paper calls for future work on tool support, automated template generation, and cross‑lingual extensions.

In conclusion, the study makes three key contributions: (1) it expands the classic interrogative set to include “Which,” thereby enriching the expressive power of requirement‑elicitation questions; (2) it provides a theoretically justified ordering of the seven interrogatives that aligns with natural reasoning and reduces ambiguity; and (3) it offers a practical, reusable pattern that helps engineers systematically capture and relate stakeholder viewpoints, ultimately leading to higher‑quality requirements analysis. The W6H framework is positioned as a valuable addition to both academic curricula and industry practice in Requirements Engineering.