  In many epidemiological contexts, disease occurrences and their rates are
naturally modelled by counting processes and their intensities, allowing an
analysis based on martingale methods. These methods lend themselves to
extensions of nested case-control sampling designs where general methods of
control selection can be easily incorporated. This same methodology allows for
extensions of the Mantel-Haenszel estimator in two main directions. First, a
variety of new sampling designs can be incorporated which can yield substantial
efficiency gains over simple random sampling. Second, the extension allows for
the treatment of multiple level time dependent exposures.
