Attack of the Killer Weeds: Methodology
The Environmental Working Group used a number of data sources in the creation of this report. The analysis of the number and trends of Section 18 exemptions was conducted using the US EPAs internal Section 18 database that we requested from the Office of Pesticide Programs. This database was broken down into a pre-1993 table and a post-1993 table. Agency staff were able to attest to the validity of the post-1993 data. They did not believe that there were any errors in the pre-1993 data; however, in the interest of research accuracy, we restricted our analysis to the more recent data.
We collected letters from members of Congress by culling the files of the Office of Pesticide Programs Field and External Affairs Division. Although our search was comprehensive, it is entirely possible that some letters were not filed properly or were not identified in our search.
Finally, our campaign finance analysis was conducted using data collected from the Federal Election Commissions campaign finance disclosure database.