What Data Quality Means

The people and jobs that read a table depend on a few rules: the data is recent, nothing is missing, values are allowed ones, no record appears twice, and related values agree. How well a dataset meets the rules its readers depend on is its data quality, measured by checks that each return a number and compare it with a threshold. A check that returns a number can run after every load, raise an alert when the number crosses its threshold, and show a trend over weeks. A remark that the data "looks wrong" can do none of these things.