THE METHODOLOGY FOR SELECTING AND INTEGRATING DATA SOURCES AND USING OFFICIAL STATISTICAL ENTERPRISE DATA, QUESTIONNAIRES, AND PROXY INDICATORS IN FORMING THE EMPIRICAL BASIS OF THE STUDY

This paper develops a methodology for constructing an empirical research database through the systematicselection and integration of multiple data sources, including official statistics, firm-level data (accounting, managerial,transactional, and registry records), survey data, and proxy indicators for hard-to-measure constructs. A practical set ofcriteria for data source selection is proposed, covering representativeness, accuracy, coverage, temporal and spatialcomparability, data preparation costs, legal and ethical constraints, and reproducibility. The data integration workflow isdescribed step by step, encompassing identifier standardization and record linkage, harmonization of measurement unitsand classifications, panel data construction, metadata management, and version control. In addition, the study outlineskey data quality checks, such as missing data diagnostics, outlier detection, internal consistency analysis, selection bias,and linkage bias, alongside documentation standards required for transparent and robust econometric research. TheResults section presents illustrative tables and conceptual figures, including a data source matrix, an integration map, aproxy indicator catalogue, and a data quality scorecard. The paper concludes with practical recommendations for buildingreliable, auditable, and replicable empirical databases in applied economic research.