premise: 1 Lower and upper PMSD bounds were determined from the 10th and 90th percentile , respectively , of PMSD data from EPA 's WET Interlaboratory Variability Study ( USEPA , 2001a ; USEPA , 2001b ) .
hypothesis: The EPA 's WET Interlaboratory Variability Study served as the reference for the upper and olwer PMSD numbers .