تم الحل ✓
categoryإحصاء
schoolبكالوريوس
event_available2026-07-15
السؤال
Transcribed Image Text:
2. (a) Dietitians are interested in the amount of nutrition people get from their food. A
dietitian carried out a pilot study which measured the calcium intake in a group
of n = 15 women aged between 25 and 50. The recommended intake of Calcium
is 1000mg per day. In the study the dietician found the sample mean was 648mg
and sample standard deviation was 476mg.
On the basis of the information here, carry out a t-test at the significance level
a = 0.05 to assess whether or not on average women are getting the recommended
amount of calcium in their diet.
(b) Later it was discovered that the dietitian had presented only a subset of the results
of the study. In fact the study looked at 5 nutrients with recommended intakes as
follows.
Variable
Calcium
Recommended Intake
1000 mg
Iron
15mg
Protein
60g
Vitamin A
800 μg
Vitamin C
75 mg
For the full study, the sample means and sample standard deviations were:
mean
s.d.
Calcium Iron Protein
A C
70 499 75
476 5
27 340 65
649 12
For the purpose of this question, the sample covariance matrix S has not been
provided. However, the following intermediate results may be useful,
-0.00257
0.5255
0.1077
-0.0049
0.0193
[-0.0001]
0.6666
0.0214
-0.0001
0.0003
where is the sample mean vector and 40 is the vector of recommended intakes.
Your task is to carry out Hotelling's T2 test on the full data at a significance level
a = 0.05. In particular, show that T2 = 53.6. State carefully the assumptions
behind the test, and the hypothesis being tested. If the null hypothesis rejected,
construct simultaneous confidence intervals to explain the reasons for rejection.
In particular, show that the simultaneous confidence interval for calcium takes the
form (56, 1242), where the values have been rounded to the nearest integer.
(c) Compare the conclusions from part (a) to the conclusions from part (b), Discuss
which analysis is is more appropriate and why.
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