Worked on improving the reliability of event loop utilization telemetry in the open-telemetry/opentelemetry-js-contrib repository, focusing on accurate delta calculations for Node.js instrumentation. Addressed a bug where non-absolute results led to incorrect delta measurements between samples by refactoring the runtime collector to use absolute values. Added a regression test to ensure the fix remained effective and maintained data quality across future changes. This work, implemented in TypeScript and leveraging Node.js performance monitoring and testing skills, enhanced the stability and accuracy of end-user metrics, reducing noise and ensuring more trustworthy event loop utilization reporting for downstream consumers of the library.