A recent study of food portion sizes reported that over a 17-year period, the av
ID: 3332610 • Letter: A
Question
A recent study of food portion sizes reported that over a 17-year period, the average size of a soft drink consumed by Americans aged 2 years and older increased from 13.1 ounces (oz) to 19.9 oz. The authors state that the difference is statistically significant with P < 0.01.† Explain what additional information you would need to compute a confidence interval for the increase, and outline the procedure that you would use for the computations. (Select all that apply.)
A. Sample sizes and standard deviations could be used to find the confidence interval. In this case we could find the interval in the usual way.
B. Sample sizes and a more accurate P-value could be used to find the confidence interval. In this case we could determine standard deviations and the confidence interval in the usual way.
C. t and degrees of freedom could be used to find the confidence interval. In this case we could compute SED and use degrees of freedom to find t*.
D. Standard deviations and degrees of freedom could be used to find the confidence interval. In this case we could now find the P-value, which could be used to find SED.
E. Degrees of freedom and a more accurate P-value could be used to find the confidence interval. In this case we could determine t, then calculate SED and t*.
Explanation / Answer
A. Sample sizes and standard deviations could be used to find the confidence interval. In this case we could find the interval in the usual way.
The correct option is ( A ) .