Various studies have shown that low data quality in bibliographic and authority records is one of the main obstacles in data management. In order to evaluate and improve data quality in the Slovenian union bibliographic database (COBIB.SI), a pragmatic dimension-based data quality measurement and evaluation case study was carried out in 2019. The article presents the set-up and application of a methodological framework that was used for the definition and measurement of bibliographic and authority records quality in COBIB.SI. The results of the case study and the framework's applicability in data quality measurement and evaluation, as well as in data profiling that would benefit further development of COBISS + catalog, are also discussed.