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Data Strategy Briefing — ISO/IEC 5259-4 Data Quality for ML

ISO/IEC 5259-4:2024 defines a process framework for managing data quality in analytics and machine-learning (ML) workflows. Part of the ISO/IEC 5259 series, this new standard extends data-quality governance beyond business intelligence to supervised, unsupervised and reinforcement learning. It emphasises structured data labelling, evaluation and lifecycle management, ensuring that training and inference data are consistently managed, measured and remediated. This briefing explains the standard’s scope, key process elements, connections to other frameworks, adoption guidance and strategic implications for data leaders.

Zeph Tech Research Lead

Research lead, Zeph Tech

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Executive summary. On 20 May 2024, ISO and the International Electrotechnical Commission (IEC) published ISO/IEC 5259‑4:2024, the latest part of the “Artificial intelligence — Data quality for analytics and machine learning” series. While Parts 1–3 establish terminology, data-quality management systems and metrics, Part 4 provides a detailed process framework for implementing high-quality data pipelines across all machine‑learning (ML) modalities. It offers prescriptive guidance on data collection, preparation, labelling, evaluation, monitoring and remediation. The standard recognises that ML outcomes are only as reliable as the data used for training and testing; therefore, it focuses on continuous quality management across an ML lifecycle. Organisations that adopt ISO/IEC 5259‑4 will strengthen traceability, reduce bias and support emerging regulatory requirements like the EU AI Act and ISO/IEC 42001.

Overview of ISO/IEC 5259‑4

ISO/IEC 5259‑4 is part of a suite of international standards designed to promote trustworthy AI. Part 1 introduces general concepts and data-quality principles. Part 2 outlines metrics and evaluation techniques. Part 3 describes how to set up a data‑quality management system (DQMS) and integrate quality processes into organisational governance. Part 4 builds on these foundations by defining a process framework for data quality specific to analytics and ML. According to the ISO catalogue, the document “defines a standardised process framework to manage data quality in analytics and machine learning” and provides guidance applicable across supervised, unsupervised, semi‑supervised and reinforcement learning【297174349272048†L140-L155】. It emphasises data labelling, evaluation and lifecycle management, ensuring that organisations implement structured approaches across diverse ML types【297174349272048†L142-L155】.

The standard highlights why data quality matters: the performance of ML models depends heavily on the quality of the data they are trained and tested on【297174349272048†L150-L156】. In supervised learning, inaccurate labelling can introduce bias or critical errors【297174349272048†L150-L156】. ISO/IEC 5259‑4 offers process‑level guidance to ensure data used for ML is consistently managed, labelled and evaluated according to industry best practice【297174349272048†L152-L155】. Benefits include high-quality training data, structured labelling guidance, applicability across ML types, stronger traceability and alignment with broader quality and lifecycle standards【297174349272048†L160-L164】.

Key components and process phases

Scope definition and planning. The standard begins by outlining how organisations should define the scope of their data‑quality activities. This includes identifying ML use cases (classification, regression, clustering, reinforcement learning), determining stakeholders (data engineers, domain experts, annotators, compliance officers) and mapping data flows from source systems to feature stores, model-training pipelines and inference services. Scoping also requires understanding legal and regulatory obligations—such as HIPAA, GDPR and the EU AI Act—to ensure that data-quality processes align with privacy and compliance requirements.

Data collection and ingestion. ISO/IEC 5259‑4 stresses that data ingestion processes must preserve integrity, provenance and traceability. Organisations should establish procedures for documenting data sources, collection methods, and consent where applicable. For ML, this may include raw sensor data, transactional logs, electronic health records, images and text corpora. The standard recommends adopting ingestion pipelines that capture metadata—timestamps, locations, sensor configurations—and storing this alongside raw data to support auditing and reproducibility.

Data preparation and labelling. A significant portion of the standard focuses on preparing data for ML. This encompasses cleansing (removing duplicates and outliers), normalisation, and feature engineering (extraction, scaling, encoding). For supervised learning, ISO/IEC 5259‑4 provides guidance on labelling practices. It urges organisations to develop labelling protocols that define label definitions, annotator qualifications, and quality control checks. The standard emphasises multi‑label and hierarchical labelling schemas when appropriate and advocates double‑blind labelling or consensus voting to mitigate bias. Documentation of labelling decisions is critical; teams should record instructions, edge cases and annotation disagreements to support transparency.

Quality metrics and evaluation. Building on ISO/IEC 5259‑2, Part 4 encourages organisations to define quality metrics relevant to their ML use cases. These may include completeness, consistency, accuracy, timeliness, credibility and provenance. The standard advises mapping these metrics to existing data observability tooling and establishing thresholds tied to model performance. For example, a decline in feature completeness might trigger retraining or human review. Evaluation should occur at multiple stages: before training, after feature engineering and during model monitoring. Implementing dashboards or scorecards helps stakeholders visualise quality trends.

Lifecycle management and monitoring. ISO/IEC 5259‑4 frames data quality as a continuous lifecycle. It mandates ongoing monitoring of data used in production ML systems to detect drift, skew and anomalies. Organisations should implement alerting when metrics deviate from thresholds and maintain processes to investigate root causes. The standard also references the need for version control of data sets, labelling guidelines and quality evaluations, enabling reproducibility and rollback when issues arise. Feedback loops—linking model performance metrics back to data-quality indicators—allow teams to identify which inputs drive outcomes.

Remediation and improvement. When quality issues are discovered, ISO/IEC 5259‑4 describes remediation strategies. These include re‑sampling data, revising labelling instructions, incorporating additional features, retraining models and updating documentation. The process framework encourages organisations to prioritise remediation based on risk and impact, ensuring that scarce resources address high‑consequence issues first. Lessons learned should feed back into scoping and planning for future projects, fostering continuous improvement.

Integrations with other standards and frameworks

ISO/IEC 5259‑4 is designed to work alongside other governance and quality frameworks. It complements ISO/IEC 5259‑3 by providing operational procedures that help organisations meet DQMS requirements【297174349272048†L181-L182】. The standard also aligns with ISO/IEC 42001, the forthcoming AI management system standard, by emphasising process discipline and documentation. Organisations may map ISO/IEC 5259‑4 processes to NIST’s AI Risk Management Framework and EU AI Act obligations. For example, the EU AI Act requires high‑risk AI systems to implement data‑governance measures that ensure training and testing datasets are relevant, representative, free of errors and complete. Adopting ISO/IEC 5259‑4 can demonstrate due diligence to regulators and auditors. Additionally, the standard supports integration with MLOps tooling—such as feature stores, data observability platforms and model monitoring services—enabling automated enforcement of quality checks.

The standard’s process guidance intersects with industry frameworks like the Data Management Body of Knowledge (DMBOK) and the FAIR principles (Findable, Accessible, Interoperable, Reusable). By embedding 5259‑4 processes into existing data‑governance programmes, organisations can unify AI data quality with enterprise data management.

Adoption and implementation guidance

Implementing ISO/IEC 5259‑4 requires coordination across data, engineering, quality and compliance teams. Organisations should begin with a gap assessment comparing current practices to the standard’s process framework. Key steps include:

  • Policy updates. Revise data‑governance policies to incorporate ISO/IEC 5259‑4 concepts, including defined roles, labelling protocols and metrics. Ensure policies reference ISO/IEC 5259‑1 to 3 and related standards such as ISO/IEC 42001 and 27001.
  • Role definition and training. Establish clear responsibilities for data owners, stewards, annotators, ML engineers and GRC personnel. Provide training on data labelling best practices, bias mitigation and the importance of high‑quality data for AI safety.
  • Tooling and automation. Integrate data-quality monitoring tools into data pipelines. Use feature stores and metadata catalogs to capture lineage and versioning. Adopt MLOps platforms that support quality gates during training and deployment.
  • Vendor and third‑party management. Extend data-quality expectations to service providers, such as labelling vendors and cloud platforms. Require evidence of compliance with ISO/IEC 5259‑4 processes in contracts. Conduct audits and request attestations.
  • Metrics and reporting. Create dashboards that track quality metrics across the ML lifecycle. Report these metrics to executives and board committees. Use trends to prioritise remediation and resource allocation.
  • Continuous improvement. Establish feedback loops where model performance insights inform data-quality efforts. Periodically review and update labelling guides, metrics thresholds and remediation playbooks. Document lessons learned and incorporate them into knowledge repositories.

Implications for organisations

Adopting ISO/IEC 5259‑4 yields several strategic benefits. High‑quality data improves model accuracy, reduces bias and supports explainability—critical factors under emerging AI regulations. The standard’s emphasis on documentation and traceability enhances audit readiness and demonstrates accountability to regulators, customers and partners. By aligning processes with international standards, organisations can more easily achieve certifications or attestations, gaining a competitive edge. The framework also encourages cross‑functional collaboration between data scientists, quality engineers, legal teams and business stakeholders, fostering a culture of data responsibility.

However, implementation requires investment. Organisations may need to upgrade tooling, retrain staff and allocate resources for ongoing monitoring. They must manage the complexity of integrating new processes with existing data‑governance frameworks and ensure that quality efforts do not slow innovation. To balance rigour with agility, teams can adopt a phased approach: prioritise high-impact ML use cases, pilot quality processes, measure benefits and scale gradually.

Zeph Tech analysis

From a Zeph Tech perspective, ISO/IEC 5259‑4 represents a pivotal shift in AI governance. While previous data-quality standards addressed traditional analytics, this new part recognises that ML systems require specialised processes to manage labelling, versioning and monitoring. For enterprise clients, we view 5259‑4 as both a compliance opportunity and a differentiator. Integrating its process framework into ML pipelines will reduce model risk and prepare organisations for forthcoming regulations like the EU AI Act. Zeph Tech advises clients to incorporate 5259‑4 controls into MLOps platforms, establish cross‑functional steering committees and update vendor requirements. The standard also pairs well with our existing guidance on NIST AI RMF and ISO/IEC 42001; together they form a comprehensive governance stack for AI development and deployment. Early adopters will be better positioned to demonstrate trustworthiness and achieve regulatory approvals in AI‑driven industries such as healthcare, finance, manufacturing and public services.

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