Validation of rules by the business is the most helpful in establishing a baseline for measuring data quality because it ensures that the rules reflect the business needs and expectations. Validation of rules by the business also helps to identify and resolve any inconsistencies or conflicts among different data sources or stakeholders. Input from customers, industry standard business definitions and built-in data error prevention application controlsare useful for improving data quality, but they are not sufficient for establishing a baseline. References: CISA Review Manual (Digital Version) 1, Chapter 5, Section 5.4.1