Statistical Problems of Merged Data Files

I. Introduction ...................... 1 II. A Statistical Model .................. 3 A. Assumptions .................... 3 B. Complications ................... 3 C. The Model and Its Application to the Transportation Problem.................... 4 III. Assumption of Conditional Independence . 7 IV. Interpretation of Matched Sampling ........... 10 V . unresolved Questions About Matching .......... 11