There is no evidence that its use improves student learning, and its implementation has had harmful side effects. The strongest finding of the research is that although merit pay programs have been tried time and again, they have always been found wanting.
Merit pay appears, spreads and then recedes like a tide.
The research on merit pay shows little to no evidence that it is effective. In a 1996 study of the Dallas schools' merit pay system, researchers Helen Ladd and Charles Clotfelter found that students had been making gains even before the program was implemented. The authors were unable to link these results to merit pay. Because there has been little other formal study of student achievement in any of the places where merit pay has been tried, the best evidence perhaps comes from the failure of the programs to endure. Further, districts were abandoning these programs long before bargaining.