How to troubleshoot inaccurate tracking data without rushing to change reports

When tracking data is inaccurate, many people's first reaction is to change the SQL or the dashboard. I usually don't touch the reports first; I break down the pipeline to see: did the frontend send it, did the gateway receive it, were the logs written, did the ETL drop anything, and finally, was the metric definition processed again? Once, the conversion rate suddenly dropped, and the business…