To study the mean blood pressure of all people in her state, Christine samples the population by dividing the residents by towns and randomly selecting 9 of the towns. She then collects data from all the residents in the selected towns. Which type of sampling is used? Stratified sampling Systematic sampling Cluster sampling Convenience sampling

Christine's sampling method is an example of cluster sampling. In this approach, the population is divided into distinct groups or "clusters" (in this case, towns), and then a random selection of clusters is chosen. By collecting data from all residents in these selected towns, Christine efficiently gathers her data while ensuring representation from different areas. Cluster sampling is especially useful when the population is widespread or difficult to access in its entirety. It can save time and resources compared to surveying every individual in a large geographic area. However, one must be cautious of potential biases if the selected clusters do not accurately represent the overall population!