Birthweight of an infant has been hypothesized to be associated with smoking status of the mother during first trimester of pregnancy. This hypothesis is tested by recording birthweights (in pounds) of infants and smoking status of mother during pregnancy for all mothers who register at the prenatal clinic at a particular hospital within a 1-month period. The mothers are divided into four groups according to smoking habit as follows:
Group 1: Mother is nonsmoker (NON)
Group 2: Mother is ex-smoker (smoked at some time before pregnancy but not during pregnancy) (EX)
Group 3: Mother is current smoker and smokes less than 1 pack per day (CUR_LS)
Group 4: Mother is current smoker and 1 pack per day or more (CUR_GR)
Are the mean of birthweights (B_WGHT) different overall in the four group (GRP)?
We analyze the data using SAS’s ANOVA procedure and observe the results shown in Table 2 Based on those findings, answer the following questions.
1) Identify the dependent variable and the independent or explanatory variable(s) in this study. Also, state the Null and Alternative hypotheses.