Football Quotient — supplementary data and code (Mannering 2026)

Supplementary data, code, and figures for: Mannering, A. (2026). Football Quotient: Quantifying National Playing Ability and the Disproportionate Returns to Development Quality in European Professional Football. SSRN Working Paper. This package supports independent verification of the empirical results and re-running of the analysis under modified assumptions. Contents:- 12 analysis-ready CSVs covering 29 European federations, including the master summary table, FIFA Big Count adjustments with authoritative source citations, professional-player counts split by domestic and abroad, CIES Monthly Report 95 expatriate extracts, CIES October 2025 Demographic Study cross-reference, birth-month distributions and per-country relative age effect statistics under both January-1 and August-1 cutoffs, Monte Carlo 95% confidence intervals (10,000 draws per nation) on each implied mean Football Quotient estimate, registration data quality flags, and a full provenance source log.- Seven Python scripts that reproduce the dataset end-to-end from the raw FIFA Big Count, CIES Monthly Reports, and Transfermarkt-derived squad inputs, including the statistical_analysis.py file that reproduces every numeric claim in Section 4 of the paper.- Three figures with source code and rendered PDF + PNG outputs. Raw third-party inputs (FIFA Big Count 2006, CIES Monthly Reports 75/85/95, CIES Demographic Study Oct 2025, Transfermarkt-derived squad data via the dcaribou/transfermarkt-datasets project) are not redistributed; the README documents where to obtain each. Citation:Mannering, A. (2026). Football Quotient: Quantifying National Playing Ability and the Disproportionate Returns to Development Quality in European Professional Football. Contact: [e-mail]