Aidoo, E.K.2024-02-122024-02-122022-04http://ugspace.ug.edu.gh:8080/handle/123456789/41219PhD. StatisticsThere are many challenges associated with both young and ageing population. If a country experiences a younger population, there’s a tendency for high unemployment rates and social vices. On the other hand, an ageing population typically results in a low labour force and high dependency ratios. Countries that tend to solve the problem of a young population initiate policies to control birth rates. However, these policies gradually lead to an ageing population before being revised, due to high costs associated with regular monitoring of population dynamics. Therefore, there is a need to develop a less costly method to monitor population dynamics and estimate the expected time to revise population policies. This study employed a more general theorem and a corollary based on ideas of probability generating functions in a branching process to come out with a method to solve the problem. The method was applied to both hypothetical and empirical data in the branching processes. The empirical data were obtained from Demographic and Health Surveys (DHS) for seven selected countries. The results from the study revealed that under certain closeness conditions, both constant and random environments yield similar results. Hence, using the method under the constant environment, which is easier, is a step in the right direction; otherwise, the proposed method for the random environment should be used. Burkina Faso recorded the youngest population, while Philippines recorded the least country with younger population. Results from the spectral analysis estimated that population policy for the selected countries should be revised between 34 to 40 years. The study recommended that the proposed model should be used to monitor population dynamics regularly. Also, population policies should be guided by appropriate time frame depending on the country’s demographic characteristics.enOffspringBranching ProcessesThesis