See: https://nepc.colorado.edu/sites/default/files/Briggs_Theeffectofadmissionstestpreparation.pdf https://nepc.colorado.edu/sites/default/files/Briggs_Theeffe.

See: https://nepc.colorado.edu/sites/default/files/Briggs_Theeffectofadmissionstestpreparation.pdf https://nepc.colorado.edu/sites/default/files/Briggs_Theeffe... "When researchers have estimated the effect of commercial test preparation programs on the SAT while taking the above factors into account, the effect of commercial test preparation has appeared relatively small"