Imagine you are interested in the relationship between maternal smoking and birthweight. Birthweight is measured in grams and maternal smoking status during pregnancy (MSmoke) is denoted with an indicator variable. You have data on maternal age and education (each measured in years) and estimate the following regression model (where _i is the error term):

Birthweight_i = + ₁Msmoke_i + ₂Age_i + ₃Education_i + _i

and obtain parameter estimates: = 3400, ₁ = -500, and ₂ = -20 and ₃ = 40

a.Providing this information, what can be interpreted for the maternal smoking parameter estimate ₁?

b.If a researcher argues that your estimate of ₁ overstates the negative effect of smoking on birthweight. Explain how the failure to account for other determinants of birthweight could lead you to overstate the negative impact of maternal smoking on birthweight.