Robert M. O'Brien is a seasoned Data & AI Associate Director with an esteemed career in a large consulting firm in the Houston area, Texas. Drawing from his extensive expertise in technology, Robert has published numerous studies and documents that have made significant contributions to the field of IT Consulting and Advanced Analytics. A man of diverse talents, who has traveled the world, he has also ventured into the realm of literature with his self-published book, "We Were Boys," a unique collection that captures real events of teenage boys through the lens of imagination. Robert aspires to devote his time to full-time writing and his current projects, weaving more intricate narratives and engaging tales that resonate with readers and expand his literary repertoire and further explore the realms of historical fiction, dystopian narratives, and beyond.

Introduction to the Age, Period, and Cohort Mix. Multiple Classification Models and Constrained Regression. Geometry of APC Models and Constrained Estimation. Estimable Functions Approach. Partitioning the Variance in APC Models. Factor-Characteristic Approach. Conclusions: An Empirical Example. Index.