A pay equity methodology document should explain exactly how the organisation moved from source HR and payroll data to its reported and analytical results. At minimum, it should identify the population, reference period, data sources, pay components, worker-category logic, working-time treatment, calculation formulas, transformations, missing-data rules, outlier treatment and review controls. Directive (EU) 2023/970 makes methodology transparency especially important because Article 9 requires management to confirm the accuracy of reported information after consulting workers' representatives, and workers' representatives must have access to the methodologies applied by the employer. The Directive does not prescribe a single document format, so employers should use a version-controlled structure that is detailed enough for another competent reviewer to reproduce the result.
Jurisdiction: European Union
A Methodology Document Explains How the Result Was Produced
A final pay-gap percentage is not enough to demonstrate how the calculation was performed. A methodology document should let a reviewer reconstruct the path from raw records to the published or internal result. It should define the population included, the reference period, the systems used, the pay fields selected, the worker-category logic and the calculations applied. This is particularly important where payroll, HR, benefits and variable-pay data are joined from different sources. Without documentation, an organisation may be able to repeat the number only because one analyst remembers the spreadsheet steps, which is not a durable control.
Article 9 Makes Methodology Transparency Operationally Important
Article 9 requires the accuracy of reported information to be confirmed by the employer's management after consulting workers' representatives. It also provides that workers' representatives shall have access to the methodologies applied by the employer. This does not mean the Directive supplies one universal methodology template. It does mean that an employer should be prepared to explain the calculation and supporting rules coherently. A documented method helps management understand what it is confirming and gives workers' representatives a meaningful basis for reviewing how worker categories, pay components and transformations were handled.
Document Population, Period and Pay Definitions First
The methodology should begin with scope. Record which legal entity or organisational population is covered, which workers are included, the reporting or measurement period and how joiners, leavers, leave periods and partial-year workers are treated. Define the pay measures used and distinguish ordinary basic wage or salary from complementary or variable components. Where gross annual and gross hourly measures are derived, state the source fields and conversion logic. These definitions should be linked to applicable national reporting guidance so that internal analytical conventions do not silently replace the methodology required for statutory reporting.
Record Every Material Data Transformation
Transformations can materially change results, so they should be explicit. The document should explain job-title normalisation, worker-category mapping, part-time treatment, annualisation, currency conversion, missing-data handling and outlier review. It should identify whether source values are preserved and which transformed fields are used in each metric. If manual exceptions exist, record who approved them and why. A short label such as data cleaned is not sufficient because it does not reveal whether records were corrected, excluded, imputed, converted or regrouped. Reproducibility depends on exposing those decisions rather than hiding them in a final spreadsheet.
Separate Required Metrics From Investigative Analytics
The methodology should distinguish calculations required for reporting from additional analytical work. Mean and median gender pay gap measures, variable-component measures, quartile distributions and category-level figures should be documented as the relevant reporting outputs. Adjusted analysis, regression, sensitivity testing and diagnostic segmentation can be documented in a separate analytical layer. This prevents a modelled adjusted result from being mistaken for a required unadjusted reporting metric. It also makes review easier because legal reporting calculations can be checked independently from broader techniques used to investigate the causes of observed differences.
Use Version Control and a Change Log
Methodology evolves as law, national guidance, systems and workforce structures change. Give each production methodology a version number and record its effective date, owner, reviewer and approval status. The change log should identify what changed and why, such as a new currency source, revised worker-category mapping or updated treatment of partial-year workers. Keep the code, formulas, query logic or transformation tables associated with the version where practicable. This makes year-to-year comparisons more reliable because analysts can distinguish a real workforce movement from a change caused by methodology.
Test Whether an Independent Reviewer Can Reproduce the Result
A practical quality test is to give the methodology, source extracts and approved transformation assets to a competent reviewer who was not involved in the original calculation. If that reviewer cannot reproduce the main metrics or identify why a record was treated a certain way, the documentation is incomplete. The review can also reveal hidden dependencies such as manual spreadsheet filters, local file paths or undocumented overrides. Reproducibility should be treated as a control objective, not merely a documentation preference, because recurring reporting and employee questions require the organisation to explain results long after the original analysis was performed.
Frequently Asked Questions
Does the EU Pay Transparency Directive require a written methodology document?
The Directive requires reporting accuracy and gives workers' representatives access to methodologies applied by the employer, but it does not prescribe one universal document template. A written, version-controlled methodology is a strong way to meet those transparency and reproducibility needs.
What should a pay equity methodology include?
It should cover population, reference period, data sources, pay definitions, worker categories, transformations, formulas, missing-data and outlier rules, analytical methods, review controls and version history.
Should regression methodology be mixed with statutory pay-gap calculations?
It is clearer to document required reporting calculations separately from adjusted or regression analysis so users can distinguish statutory metrics from investigative analytics.
Related Guides
Official Sources
Requirements and practices differ by jurisdiction and organisation. Check current local law, official guidance and professional advice for a specific situation.