Which of the following is an example of a secondary data source?

A cancer registry is considered a secondary data source because it compiles and analyzes data collected from various primary sources, such as hospitals and treatment facilities, about cancer patients. This type of data collection focuses on aggregating information for public health and research purposes, rather than providing real-time data for individual patient care.

Secondary data sources are important as they provide broader insights into health trends, epidemiology, and resource allocation without the direct involvement of the clinical care process. They typically summarize or analyze information that has already been gathered through primary sources, which are directly related to patient care, such as laboratory reports, pathology reports, and individual patient records. Therefore, in the context of this question, the cancer registry exemplifies a secondary data source effectively because it pulls from multiple primary sources to inform public health and research initiatives.