Evaluating the relationship between smoking during pregnancy and birth weight

The state of North Carolina released to the public a large data set containing information on births recorded in this state. This data set has been of interest to medical researchers who are studying the relation between habits and practices of expectant mothers and the birth of their children. ncbirths is a random sample of 1000 cases from this data set. We want to evaluate whether there is a difference between weights of babies born to smoker and non-smoker mothers.