Attributable Risk

Part 1: Attributable Risk (26 points, 2 points each) 

Table 1: Two by Two Table for Study of Smoking during Pregnancy and Low Birth Weight Infants

Low Birth Weight Normal Birth Weight Total

Smoked during Pregnancy 19 139 158

Did not Smoke during Pregnancy 53 789 842

Total 72 928 1000

Based on the above 2 by 2 table, answer the following questions.  Please show all steps in all calculations.

1)    Assuming these data came from a cohort study, calculate the incidence of giving birth to a low-birth-weight baby among mothers who had smoked during pregnancy.  Express the final answer as a percentage, rounding to one place after the decimal.

2)         Calculate the incidence of giving birth to a low-birth-weight infant among mothers who had not smoked during pregnancy.  Express the final answer as a percentage, rounding to one place after the decimal.

3)         Calculate the incidence of giving birth to a low-birth-weight infant among the entire sample of mothers.  Express the final answer as a percentage, rounding to one place after the decimal.

4)         Calculate the relative risk of the association between maternal smoking during pregnancy and giving birth to a low-birth-weight baby. Round to two places after the decimal.

5)      Calculate the prevalence of smoking during pregnancy in this sample.  Express the final answer as a percentage, rounding to one place after the decimal.

6)         Calculate the risk difference of giving birth to a low-birth-weight infant between mothers who smoked and did not smoke during pregnancy.  Express the final answer as a percentage, rounding to one place after the decimal.

7)        Calculate the attributable risk of maternal smoking on the incidence of having a low-birth-weight baby among those mothers who smoked during pregnancy.  Express the final answer as a percentage, rounding to one place after the decimal.

8)         interpret the  in one sentence.

9)         Calculate the population risk difference. Express the final answer as a percentage, rounding to one place after the decimal.

10)       Calculate the population attributable risk of smoking during pregnancy on having a low-birth-weight baby in the whole sample. Express the final answer as a percentage, rounding to one place after the decimal.

11)        interpret the  in one sentence.

12)       If the prevalence of smoking during pregnancy were to increase, what would happen to the population attributable risk?

13)       If the relative risk had been lower, what would happen to the population attributable risk?