Population Projection Based on the Cohort-Component Method: A Comparative Study of Global and Indonesian Approaches

This study aims to examine the population growth projections of Indonesia and the world for the period 2020–2050 using the cohort-component method. It also compares the projection approaches used by Statistics Indonesia (BPS) and the United Nations (UN), and evaluates the strengths and limitations of the method in both national and global contexts. The research was conducted through a review of official projection documents, descriptive analysis of demographic trends (population size, TFR, births, deaths, and migration), and methodological evaluation based on technical documentation. The findings indicate that both Indonesia and the world are experiencing declining population growth rates and fertility levels through 2050, although Indonesia is projected to maintain positive growth. BPS employs a deterministic approach using policy-based scenarios, while the UN adopts a probabilistic, Bayesian-based approach. The evaluation reveals that the cohort-component method offers advantages in age structure accuracy and application flexibility, yet it also has limitations related to assumptions and reliance on data quality. These findings highlight the importance of adaptive approaches in demographic projections to support data-driven development planning.