Maternal Smoking and Infant Health


How do babies born to smokers compare to babies born to non-smokers?

To answer this question, you are provided the birth weights of all baby boys born in one year at the Kaiser Hospital in Oakland. The babies weights are reported in ounces (16 ounces to the pound and 35 ounces to the kilogram). These data are split into two groups: For now, we will ignore the group of babies born to women who used to smoke but quit while pregnant.

Answer the following questions. Print any 4 plots that you use in answering the questions, and print a copy of the transcript that records your computations. Include these plots and the transcript along with this handout, when turning in your assignment.

Assessing the fit of the Normal Distribution

How would you describe the shape of the distribution of birth weights for babies born to smokers?

1. Modality:
unimodal bimodal flat

 

2. Symmetry:
symmetric skewed left skewed right

 

3. Tails:
normal long left long right short

 

4. Does the distribution of birth weight for the babies born to smokers appear to be roughly normal?
Provide supporting evidence for your answer from at least two different graphical or numerical summaries.

 

5. Does the distribution of birth weight for the babies born to smokers appear to be similar in shape to the distribution for non-smokers?
Explain.

 

Numerical Summaries

When the data look roughly normal, the mean and SD provide reasonable summaries of the distribution. The mean provides the center of the distribution, and the SD denotes the spread, i.e. roughly how far from the center you might expect a baby's birth weight to be. If the data do not appear to be normally distributed then quantiles offer a more appropriate summary of the data.

6. The birth weights of all the babies fall roughly between
45 55 60 65 75 85 ounces
and
145 155 165 175 185 ounces

 

7. Compare the center of the two birth weight distributions.

 

8. Compare the spread of the two distributions.

 

Low-Birthweight Babies

Babies born that weigh under 5.5 pounds, or 88 ounces, are termed low birth-weight.

 

9. What percentage of babies born to smokers are low birth-weight?
What percentage of babies born to non-smokers are low birth-weight?

 

10. In 2001, about 4 million babies were born in the United States. Roughly 15% of the mothers of these babies smoked during their pregnancies. Assume the rate of low birthweight babies is that found in question 9 for smokers and nonsmokers. How would the number of low birthweight babies born in 2001 change, if all pregnancies had the rate of the nonsmokers.

 

11. Are the differences you found in your analysis important? That is, are these low birth weight babies less healthy?

Support your answer with at least two quotes from the background material found on pages 3-7 in the Stat Labs book.