“…The research in this area is equivocal. A number of recent studies using objectively measured data, such as urinalysis, along with self-report measures of recent stimulant drug-use, found poor concordance between these measures (Chermack et al, 2000;Ehrman et al, 1997;Fendrich et al, 2004;Kilpatrick, Howlett, Sedgwick, & Ghodse, 2000; Lu, Taylor, Bruce, & Riley, 200;Tassiopoulos et al, 2004). However, others have reported a reasonable degree of concordance between self reported and objectively measured stimulant drug use (Darke, 1998;Yacoubian, & Urbach, 2002), especially when subjects are not seeking actual drug use/abuse treatment (Elman et al, 2000).…”