A Goal–Question–Metric (GQM)-Based Framework for Measuring the Quality of Legacy Software Systems in Organizational Environments

Abstract

Legacy software systems remain central to many organizations, yet their quality is often assessed through general descriptions rather than systematic measurement. This paper proposes a structured Goal–Question–Metric (GQM)-based framework for measuring the quality of legacy software systems within organizational technical environments. The framework was developed through repeated GQM sessions, workshops, and extended discussions with technical leaders and specialists, with emphasis on objective and quantifiable metrics. It examines legacy software system quality through indicators related to vendor license and support, internal support, programming-language condition, technical-update documentation, business-process alignment, user satisfaction, user complaints, security breaches, documentation types, and fundamental problems. By translating quality assessment into an explicit goal, focused questions, measurable indicators, and interpretable numerical formulations, the proposed framework supports clearer evaluation of whether a legacy software system remains manageable, requires closer monitoring, or represents a quality-related risk. The proposed formulation is validated through case studies using real organizational data from public, private, semi-government, and international contexts. The validation results demonstrate how the quality measure can distinguish acceptable, pre-risk, and risk conditions and support more informed decisions regarding maintenance, modernization, reengineering, or replacement.