No theory forbids me to say "Ah!" or "Ugh!", but it forbids me the bogus theorization of my "Ah!" and "Ugh!" - the value judgments. - Theodor Julius Geiger (1960)

Measuring Human Factors?

As W. Edwards Deming wrote, when we work in quality, management, and leadership, we have to (1) understand systems, (2) know how things change, (3) use theories to understand things, and (4) know how people think and act. The last part is crucial for people who work in health and safety, and try to use metrics.

As Jerry Muller shows in his book "The Tyranny of Metrics":
-      Human activity is complex and reactive, making measurements LESS reliable than measurements of objects, especially when tied to rewards or punishments.
-      NOT everything measurable is worth measuring. Ask if the information gathered truly aligns with the goals intended and if it serves as a valid proxy for what's essential.
-      Metrics excel in pinpointing outliers, but the marginal cost of MORE measurement might outweigh the benefits, particularly for those in the middle or top performers.
-      Understand who will use the information and for what PURPOSE. Metrics for internal evaluation are distinct from those used for external reward/punishment and might lead to different reactions.
-      Consider the COSTS of acquiring metrics in terms of time, effort, and distraction from actual work. Also, ponder why top management demands metrics and the INVOLVEMENT of stakeholders in developing them.
-      Even the best measures can be corrupted or diverted from intended goals. Acknowledge the limitations and the SUBJECTIVE nature of certain aspects that metrics might fail to capture.
-      Not every problem is solvable or improved by measurement. Recognize the importance of EXPERIENCE, unquantifiable skills, and the limitations of standardized metrics in informing judgment.
As Carsten Busch writes in his book it's wise to find a balance and combine measurements with rich sources of information. As for existing measurements: ask questions and "do not try to change the world in one day".

Metrics should inform judgment rather than replace it.

Busch, C. (2019), If You Can't Measure It - Maybe You Shouldn't - Reflections on Measuring Safety, Indicators, and Goals, Mysen: Mind The Risk.
Muller, J.Z. (2018), The Tyranny of Metrics, Princeton NJ: Princeton University Press.