system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Serial interval measures
assistant
The correct answer is  .serial inetrval is the time gap between the onset of primary cases and the secondary cases.by collecting information on the whole series if such onsets,we get a distribution of secondary cases from which we can guess the incubation period of disease. ref:park&;s textbook ,22 nd edition,pg no 96