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Thread: Confidence interval for a difference of means between two samples.

  1. #1
    Apr 2010

    Confidence interval for a difference of means between two samples.

    Considerable effort has been expended examining the effects of breast-feeding and bottle-feeding on the subsequent health of infants. In one such study a specialised device was developed to measure blood pressure in infants, and mean systolic blood pressure (SBP) was measured at 1 month of age. The following descriptive statistics are classified according to feeding status recorded in hospital a few days after birth.

    feeding status in hospital Mean SBP (mm Hg) Standard deviation Count
    Breast-fed 77.9 9.53 123
    Bottle-fed 81.5 9.23 97

    a) Provide a 99% confidence interval for the difference in mean SBP at 1 month of age between breast-fed and bottle-fed infants.

    b) The validity of the confidence interval in part (a) depends on some statistical assumptions. In assessing whether those assumptions are reasonable for the data, what use could be made of histograms of the two samples? Justify your answer.

    c) Indicate, with reasons, any aspects of the study that may affect the validity of the data.

    can someone give me a hand for this question?
    much appreciated
    Last edited by mr fantastic; Apr 25th 2010 at 04:36 PM. Reason: Re-titled post.
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