How Do You Ensure Data Quality?

Quality Gates and Contracts When an interviewer asks 'how do you ensure data quality,' they're testing whether you think in layers or just say 'we check for nulls.' The trap is giving a single tool answer ('we use Great Expectations'). Your answer should name three layers immediately: contract tests at the schema level, content tests at the value level, and anomaly detection at the distribution level. Then give a concrete example of each. The follow-up will be: 'What happens when a test fails?' The red flag is 'we log a warning.' The senior signal is 'the pipeline halts and blocks promotion to the next layer.' Interviewers have specifically called out that candidates who say 'log and continue' get downgraded on the reliability rubric. The interviewer wants to hear you connect tools to the