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MILITARY UNIT AND HERBICIDE SPRAYING DATABASES, AND EXPOSURE ASSESSMENT MODEL DEVELOPMENT 13 Database-Vietnam (MUD-V),â although not intended for epidemiologic purposes, was viewed as a prototype for the present study. The Columbia University researchers undertook to examine the extent of coverage of the MUD-V database, evaluate gaps in the data, assess the implications of misclassification of exposure, andâgiven all these considerationsâascertain how much usable information remained for epidemiologic investigations. One aim of Project 1 was to carry out a sensitivity analysis of the data in MUD-V to determine the extent to which it could satisfactorily produce a rank-ordered exposure rating for the military units. On the basis of their previous experiences, the Columbia University researchers concluded that many so- called gaps or inconsistencies in the secondary data sources were minor and would not seriously affect the accuracy of epidemiologic studies. Indeed, they had developed methods in the AOVPP for imputing reasonable locations and exposure scores where data were missing, such as substituting average battalion locations for companies or using the highest computed exposure among companies with known locations for a company whose location during a particular period was not known. Nonetheless, one of the immediate tasks undertaken in this contract was to re-examine the database and remove all imputed data. To accomplish that, the researchers returned to the original troop-movement data that had been collected by the US Army and Joint Services Environmental Services Group (ESG), now known as the US Joint Services Center for Research of Unit Records. Restoring the Troop-Movement Database The original troop-movement database was stored on 9-in. magnetic reels in virtual address extension (VAX) backup format, which is no longer manufactured. Recovery entailed first locating a working Digital Equipment Corporation VAX and obtaining licenses for appropriate operating systems and other software. Eventually, the original data and directory structure were restored, original research notebooks were located, and data were made compatible with current
