Final answer:
The number of new and existing cases of obesity in the US in 2001 describes the prevalence of obesity, which includes all cases in a given population during a specified period. Incidence, in contrast, only accounts for new cases in a specific time frame.
Step-by-step explanation:
The number of new and existing cases of obesity in the US in 2001 describes the prevalence of obesity. Prevalence accounts for all individuals with a condition in a given population during a specified period, including those with newly diagnosed cases as well as those who have already been living with the condition. Therefore, when a research article talks about the number of new and existing cases, it is referring to the prevalence of the condition in the community or population.
In contrast, incidence refers only to the number of new cases that develop in a specific time period. Understanding the difference between these two terms is critical for interpreting health research and statistics related to various diseases, including obesity, which is a significant global health challenge due to its rising prevalence and associated health outcomes.