Summary

The issues raised in this chapter point to limitations in the original design of the longitudinal study as well as to additional considerations that result from the restrictions in the pool of data available for the follow-up. We have addressed each concern with the best of our knowledge and ability, given the limitations of the data. We feel confident that, in identifying the potential confounders, we have laid the most important concerns to rest; the specifics of the analytic strategy that we used to deal with these concerns are described in Chapter VI.