What are common data quality indicators or flags used in QA/QC?

• A. Calibration status flags indicate instrument health.
• B. Valid, suspect, invalid, not available.
• C. Active, passive, novel, obsolete.
• D. Green, yellow, red, blue.

Answer: (B)

Data quality flags label each measurement with how trustworthy it is for analysis. The most common four-category set used in QA/QC is valid, suspect, invalid, not available. Valid means the value has passed all quality checks and can be used without special handling. Suspect indicates there are concerns—perhaps a sensor issue or an anomalous reading—so the data should be reviewed or treated with caution. Invalid means the data failed QA/QC and should be excluded from analyses. Not available means the value wasn’t collected or can’t be reported, so it cannot be used. These flags make automated filtering, quality reporting, and traceability of data quality over time straightforward.

Other notions like calibration status flags focus on instrument health rather than per-measure data quality. Lifecycle terms such as active, passive, novel, obsolete describe usage or status of devices rather than the quality of individual data points. Color codes like green, yellow, red, blue can convey status in a UI but aren’t the standardized data quality categories used to annotate measurements in QA/QC workflows.