Table 3. Stimulant-use assignment for study week as a function of time line follow back and stimulant urine drug screen results.

Urine Drug Screen -Stimulant result		Time Line Follow Back (TLFB)
Result	Result	At least one positive day	All days negative	Some days negative, some missing	All days missing
-	-	+	-	-	-
+	-	+	+	+	+
+	+	+	+	+	+
+	0	+	+	+	+
0	0	+	Missing	Missing	Missing
-	0	+	-	-	-

^**Note: '0′=missing, '+'=positive and '-'=negative