Childbirth, part 5. In Exercises 13, 15, 17, and 19, we’ve looked at a study examining epidurals as one factor that might inhibit successful breastfeeding of newborn babies. Suppose a broader study included several additional issues, including whether the mother drank alcohol, whether this was a first child, and whether the parents occasionally supplemented breastfeeding with bottled formula. Why would it not be appropriate to use chi-square methods on the 2 × 8 table with yes/no columns for each potential factor?

Exercise 19:

Childbirth, part 4. In Exercises 13, 15, and 17, we’ve tested a hypothesis about the impact of epidurals on successful breastfeeding. The table shows the test s residuals.

a) Show how the residual for the epidural/no breastfeeding cell was calculated.

b) What can you conclude from the standardized residuals?

Exercise 17:

Childbirth, part 3. In Exercises 13 and 15, we’ve begun to examine the possible impact of epidurals on successful breastfeeding.

a) Calculate the component of chi-square for the epidural/no breastfeeding cell.

b) For this test, What’s the P-value?

c) State your conclusion.

Exercise 15:

Childbirth, part 2. In Exercise 13, the table shows results of a study investigating whether aftereffects of epidurals administered during childbirth might interfere with successful breastfeeding. We’re planning to do a chisquare test.

a) How many degrees of freedom are there?

b) The smallest expected count will be in the epidural/ no breastfeeding cell. What is it?

c) Check the assumptions and conditions for inference.

Exercise 13:

Childbirth, part 1. There is some concern that if a woman has an epidural to reduce pain during childbirth, the drug can get into the baby s bloodstream, making the baby sleepier and less willing to breastfeed. In December 2006, the International Breastfeeding Journal published results of a study conducted at Sydney University. Researchers followed up on 1178 births, noting whether the mother had an epidural and whether the baby was still nursing after 6 months. Results are summarized in the table.

a) What kind of test would be appropriate?

b) State the null and alternative hypotheses.