A recent study of food portion sizes reported that over a 17-year period, the av

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.)

1) 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*.

2) 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.

3) 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.

4) 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.

5) 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*.

Do you think that a confidence interval would provide useful additional information? Explain why or why not.

1) No, the confidence interval could give us no more useful information because the P-value already tells us that the interval does not contain 0

2) Yes, the confidence interval could give us useful information about the variability between sample participants in the study.

3 )No, the confidence interval could give us no more useful information because it cannot tell us the sample size in the study.

4) Yes, the confidence interval could give us useful information about the magnitude of the difference.

5) Yes, the confidence interval could give us useful information about the average size of soft drinks.

Here are the attempts I have already made based on other Chegg posts:

For the 1st question, I tried 4 and 5, then I tried 2 and 4, and then I tired 2 3 and 5.

for the 2nd question I tried 3, then 5, then 1.

Explanation / Answer

Solution:-

I) Only 1, 2 and 5 are correct.

1) 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*.

2) 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.

5) 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*.

II) Only 4

4) Yes, the confidence interval could give us useful information about the magnitude of the difference.

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