The Age-Period-Cohort-Interaction Model for Describing and Investigating Inter-Cohort Deviations and Intra-Cohort Life-Course Dynamics

TL;DR

The paper introduces the APC-I model, a new approach for analyzing age, period, and cohort effects that captures inter-cohort deviations and intra-cohort dynamics without problematic assumptions.

Contribution

It proposes a novel age-period-cohort-interaction model that aligns with theoretical concepts and allows straightforward interpretation and hypothesis testing.

Findings

Applied to women's labor force participation data.

Identified significant inter-cohort deviations.

Enabled hypothesis testing on intra-cohort dynamics.

Abstract

Social scientists have frequently sought to understand the distinct effects of age, period, and cohort, but disaggregation of the three dimensions is difficult because cohort = period - age. We argue that this technical difficulty reflects a disconnection between how cohort effect is conceptualized and how it is modeled in the traditional age-period-cohort framework. We propose a new method, called the age-period-cohort-interaction (APC-I) model, that is qualitatively different from previous methods in that it represents Ryder's (1965) theoretical account about the conditions under which cohort differentiation may arise. This APC-I model does not require problematic statistical assumptions and the interpretation is straightforward. It quantifies inter-cohort deviations from the age and period main effects and also permits hypothesis testing about intra-cohort life-course dynamics. We demonstrate how this new model can be used to examine age, period, and cohort patterns in women's labor force participation.