Question

The Tomz Store takes periodic randomized surveys to track health of Americans. In a survey of 4881 adults in 2007-2008, 1674 were obese (body mass index BMI ≥ 30). In a survey of 5181 adults in 2011-2012, 1808 were obese.

1.)   Estimate with 95% confidence the change in the population proportion from the first survey to the second survey that were obese and interpret the results.

2.)   The standard error for this difference is quite small. What is the primary reason that causes the SE to be so small?

Answer 1