The importance of the prices’ study has increased quickly in the last years: several national statistical agencies started developing projects based on longitudinal studies to measure the movements of the prices of products and services. Many methodological issues are subject of intensive research to improve the quality of the whole indexes’ production process. The target of this work is to contribute to improve the quality of the data collection process by studying the temporal evolution of the survey data. Starting from a simulated population, a number of commonly used sample selection methods are compared underlining their relative efficiency and evaluating how and how much the change in the size measure over time affects the estimates and the bias of the results.