President Obama today (10 Mar 2009), as part of his call for renewed focus on education in the United States, repeated his call for using merit pay to reward teachers.
Teachers' unions have consistently opposed merit pay provisions in their contract negotiations. Perhaps they mistrust who will be passing judgment on the merit of each teacher. Considering that favoritism is a potential problem in all areas of economic relations, that is a valid concern.
We can no longer ignore, however, that some teachers are vastly superior to some of their counterparts and deserve to be financially rewarded for that excellence. The question of how excellence measured should be reduced to students' performance on tests. The question of which tests should be used for this can be left up to individual states, districts or even schools, but it has to be something quantifiable.
It is not enough to say that teachers with the highest performing students should be rewarded the most. They could have inherited a smarter group or, more likely, been assigned a smarter group based on their seniority or personal connections with other school personnel. When money is at stake, people will cheat, teachers included. Instead, merit pay should be based on the average <i>improvement</i> of each student's score over the prior year's assessment. This means that if a particular student does not have both a current and prior year assessment, there is no improvement to be measured and that score is removed from the improvement calculation. (For math geeks ...) There may be situations where the level of improvement is identical across different teachers' student bodies. In this case it may make sense to compare the current's year's improvement with the student's previous year improvement (in essence, taking the second derivative of improvement), rewarding those teachers who helped students improve more than they did the prior year.
The old arguments against merit pay are a useless barrier to engendering excellence in teaching. A simple computer spreadsheet is all the technology needed to distill all the information necessary to find out who's doing the best job with our students. The only question left should be by how much the best teachers' pay raises should exceed the worst.