What is a line listing and what purpose does it serve?

• A. A narrative report of outbreak chronology.
• B. A chart summarizing the number of cases by day.
• C. A financial ledger of outbreak expenses.
• D. A tabular dataset of cases with key attributes used to characterize and analyze the outbreak.

Answer: (D)

A line listing is a tabular dataset where each row represents a single case and each column captures a key attribute of that case, such as onset date, exposure, age, sex, location, laboratory result, and outcome. Its purpose is to organize case-level information so investigators can clearly describe who is affected, where the cases are occurring, and when events happen, enabling meaningful analysis of the outbreak. With this dataset, you can summarize distributions by person, place, and time, identify common exposures, detect clusters, and perform further analyses (like calculating rates or preparing for analytical studies). It also helps with data cleaning and keeping a working, up-to-date record as new cases arrive. This differs from a narrative outbreak chronology, which tells a story of events, or from a simple chart of cases by day, which provides counts rather than detailed case information.