What are the challenges associated with population forecasting?

Population forecasting is challenging because it involves predicting future demographic trends, which are influenced by a wide range of factors such as economic, social, and political changes. The accuracy of population forecasts depends on the quality and reliability of the data used, which can be affected by data gaps, errors, and biases. In addition, unforeseen events such as natural disasters or pandemics can significantly affect population growth and migration patterns. Finally, population forecasting can be controversial as it involves making assumptions about future trends that may not reflect the reality.