Occupational Cohort Time Scales.

PURPOSE

This study explores how highly correlated time variables (occupational cohort time scales) contribute to confounding and ambiguity of interpretation.

METHODS

Occupational cohort time scales were identified and organized through simple equations of three time scales (relational triads) and the connections between these triads (time scale web). The behavior of the time scales was examined when constraints were imposed on variable ranges and interrelationships.

RESULTS

Constraints on a time scale in a triad create high correlations between the other two time scales. These correlations combine with the connections between relational triads to produce association paths. High correlation between time scales leads to ambiguity of interpretation.

CONCLUSIONS

Understanding the properties of occupational cohort time scales, their relational triads, and the time scale web is helpful in understanding the origins of otherwise obscure confounding bias and ambiguity of interpretation.