Question

Scientists and engineers frequently wish to compare two different techniques for measuring or determining the value of a variable. In such situations, interest centers on testing whether the mean difference in measurements is zero. An article reports the accompanying data on amount of milk ingested by each of 14 randomly selected infants.

	Infant
	1	2	3	4	5	6	7	8	9	10	11	12	13	14
DD method	1509	1418	1561	1556	2169	1730	1098	1198	1479	1281	1414	1964	2174	2058
TW method	1498	1254	1356	1565	2000	1318	1410	1129	1342	1124	1468	1604	1722	1548
Difference	11	164	205	−9	169	412	−312	69	137	157	−54	360	452	510

(a)

Is it plausible that the population distribution of differences is normal?

No. The normal probability plot is not reasonably straight, so it's not plausible that time differences follow a normal distribution and the paired t-interval is not valid.No. The normal probability plot is reasonably straight, so it's not plausible that time differences follow a normal distribution and the paired t-interval is not valid.    Yes. The normal probability plot is reasonably straight, so it's plausible that time differences follow a normal distribution and the paired t-interval is valid.Yes. The normal probability plot is not reasonably straight, so it's plausible that time differences follow a normal distribution and the paired t-interval is valid.

(b)

Does it appear that the true average difference between intake values measured by the two methods is something other than zero? Determine the P-value of the test, and use it to reach a conclusion at significance level 0.05.

Calculate the test statistic and P-value. (Round your test statistic to two decimal places and your P-value to three decimal places.)

t=P-value=

State the conclusion in the problem context.

Fail to reject H₀. The data suggests that the true average difference between intake values measured by the two methods is something other than zero.Reject H₀. The data suggests that the true average difference between intake values measured by the two methods is something other than zero.    Reject H₀. The data does not suggest that the true average difference between intake values measured by the two methods is something other than zero.Fail to reject H₀. The data does not suggest that the true average difference between intake values measured by the two methods is something other than zero.

Answer 1