In: Statistics and Probability
A study of fast-food intake is described the the paper "What
People Buy From Fast-Food Restaurants"...
A study of fast-food intake is described the the paper "What
People Buy From Fast-Food Restaurants" (Obesity, 2009,
pages 1369-1374). Adult customers at three hamburger chains
(McDonald's, Burger King and Wendy's) in New York City were
approached as they entered the restaurant at lunchtime and asked to
provide their receipt when exiting. The receipts were then used to
determine what was purchased and the number of calories consumed
was determined. In all, 3857 people participated in the study. The
sample mean number of calories consumed was 857 with a sample
standard deviation of 677.
- The sample standard deviation is quite large. What does this
tell you about the number of calories consumed in a hamburger-chain
lunchtime fast-food meal in New York City?
- Given the values of the sample mean and standard deviation and
the fact that the number of calories cannot be negative, explain
why it is not reasonable to assume that the distribution of
calories consumed is Normal.
- Based on a daily intake of 2000 calories, 750 calories for
lunch is recommended. Assuming that it is reasonable to regard the
sample of 3857 fast-food purchases as representative of all
hamburger-chain lunchtime purchases in New York City, carry out a
hypothesis test to determine if the sample provides convincing
evidence that the mean number of calories in a New York City
hamburger-chain lunchtime purchase is greater than 750
calories.
- Is it reasonable to generalize the conclusion of the hypothesis
test to the lunchtime fast-food purchases of all adult Americans?
Explain why or why not.
- Explain why it is better to use the customer receipt to
determine what was ordered rather than just asking a customer
leaving the restaurant what they ordered.
- Do you think that asking a customer to provide their receipt
before they ordered could have introduced a bias? Explain.