There were a number of factors we did not include in our study that could have influenced—and indeed probably did influence—the skill levels of the violinists in the different groups. For instance, students who were lucky enough to have worked with exceptional teachers would likely have progressed more quickly than those with teachers who were just okay.
Padahal ini penting gak sih, akses yg dimiliki orang dg latar belakang sosio-ekonomi yg beda pasti beda juga, walau utk sampel ini bisa diasumsikan semua murid datang dari kelas yg relatif sama krn sekolahnya sama
