In: Statistics and Probability
A study of iron deficiency among infants compared samples of infants following different feeding regimens. One group contained breast-fed infants, while the infants in another group were fed a standard baby formula without any iron supplements. Here are summary results on blood hemoglobin levels at 12 months of age.
Group | n | x | s |
---|---|---|---|
Breast-fed | 24 | 13.1 | 1.5 |
Formula | 18 | 12.6 | 1.6 |
(a)
Is there significant evidence that the mean hemoglobin level is higher among breast-fed babies? State H0 and Ha.
H0: μbreast-fed > μformula; Ha: μbreast-fed = μformulaH0: μbreast-fed ≠ μformula; Ha: μbreast-fed < μformula H0: μbreast-fed = μformula; Ha: μbreast-fed > μformulaH0: μbreast-fed < μformula; Ha: μbreast-fed = μformula
Carry out a t test. Give the P-value. (Use α = 0.01. Use μbreast-fed − μformula. Round your value for t to three decimal places, and round your P-value to four decimal places.)
t | = | |
P-value | = |
What is your conclusion?
Reject the null hypothesis. There is not significant evidence that the mean hemoglobin level is higher among breast-fed babies.Fail to reject the null hypothesis. There is significant evidence that the mean hemoglobin level is higher among breast-fed babies. Fail to reject the null hypothesis. There is not significant evidence that the mean hemoglobin level is higher among breast-fed babies.Reject the null hypothesis. There is significant evidence that the mean hemoglobin level is higher among breast-fed babies.
(b)
Give a 95% confidence interval for the mean difference in hemoglobin level between the two populations of infants. (Round your answers to three decimal places.)
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