# Question

It is well-documented that active maternal smoking during pregnancy is associated with lower-birth-weight babies. Researchers Fernando D. Martinez and associates wanted to determine if there is a relationship between paternal smoking habits and birth weight. The researchers administered a questionnaire to each parent of newborn infants. One question asked whether the individual smoked regularly. Because the survey was administered within 15 days of birth, it was assumed that any regular smokers were also regular smokers during pregnancy. Birth weights for the babies (in grams) of nonsmoking mothers were obtained and divided into two groups, nonsmoking fathers and smoking fathers. The given data on the next page are representative of the data collected by the researchers. The researchers concluded that the birth weight of babies whose father smoked was less than the birth weight of babies whose father did not smoke.

(a) Is this an observational study or a designed experiment? Why?

(b) What is the explanatory variable? What is the response variable?

(c) Can you think of any lurking variables that may affect the results of the study?

(d) In the article, the researchers stated that "birthweights were adjusted for possible confounders ...." What does this mean?

(e) Determine summary statistics (mean, median, standard deviation, quartiles) for each group.

(f) Interpret the first quartile for both the nonsmoker and smoker group.

(g) Draw a side-by-side boxplot of the data. Does the side-by-side boxplot confirm the conclusions of the study?

(a) Is this an observational study or a designed experiment? Why?

(b) What is the explanatory variable? What is the response variable?

(c) Can you think of any lurking variables that may affect the results of the study?

(d) In the article, the researchers stated that "birthweights were adjusted for possible confounders ...." What does this mean?

(e) Determine summary statistics (mean, median, standard deviation, quartiles) for each group.

(f) Interpret the first quartile for both the nonsmoker and smoker group.

(g) Draw a side-by-side boxplot of the data. Does the side-by-side boxplot confirm the conclusions of the study?

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