Lokhu kuyoba appendix lobuchwepheshe ohlakeni imiPhumela yokuFunda kumiphumela yokuhlaziya ezingase zivele; ukuze uthole olunye ulwazi, bheka Morgan and Winship (2014) kanye Imbens and Rubin (2015) . Isithasiselo ngeke ukuveza imibono elandelayo mayelana kwemiphumela engahle ibe khona:
Isithasiselo ayohlanganisa ukuqhathanisa phakathi-tifundvo, ngaphakathi-izikhonzi, futhi imiklamo exubile. Isithasiselo kungase kuhlanganise ukwaziswa mayelana ngokusebenzisa ilwazi pre-ukwelashwa ngoba design noma ukuhlaziya.