Self-report vs electronic monitoring: stratified analyses. Adjusted mean days of 6MP intake by generalized estimating equation analysis for self-report vs electronic (MEMS) monitoring by study month stratified by (A) racial/ethnic groups ([i] non-Hispanic whites, [ii] Hispanics, [iii] Asians, and [iv] African Americans; (B) paternal education ([i] college degree or higher and [ii] less than a college degree); (C) 6MP adherence rate ([i] ≥95% and [ii] <95%).