Question

it is well - documented that active maternal smoking during pregnancy is associated with lower - birth - weight babies. researchers 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 accompanying data are representative of the data collected by the researchers. the researchers concluded that the birth weight of babies whose father did not smoke. complete parts (a) through (g) below. (a) is this an observational study or a designed experiment? why? it is an observational study because the researchers did not intentionally change the value of an explanatory variable. (b) what is the explanatory variable? what is the response variable? the explanatory variable is the response variable is

Explanation:

(a) Step1: Determine study nature

Researchers observed without manipulation.

(a) Step2: Classify study type

It is an observational study.

(b) Step1: Identify explanatory variable

Variable influencing outcome: paternal smoking status.

(b) Step2: Identify response variable

Outcome measured: birth weight of babies.

Answer:

(a) It is an observational study because researchers did not intentionally change the explanatory variable (paternal smoking status) but observed existing groups.
(b) The explanatory variable is paternal smoking status; the response variable is birth weight of babies.