Everyone interested in understanding how the ceaseless pressure to raise test scores can corrupt the tests should be familiar with Campbell’s Law.

This is an adage written by social scientist Donald T. Campbell in a 1976 paper. It says:

“The more any quantitative social indicator is used for social decision-making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor.” (You can google the paper, or find it linked on Wikipedia: Campbell, Donald T., Assessing the Impact of Planned Social Change The Public Affairs Center, Dartmouth College, Hanover New Hampshire, USA. December, 1976.)

Campbell’s Law explains why high-stakes testing promotes cheating, narrowing the curriculum, teaching to the test, and other negative behaviors..

In his 1976 paper, Campbell also wrote that  “achievement tests may well be valuable indicators of general school achievement under conditions of normal teaching aimed at general competence. But when test scores become the goal of the teaching process, they both lose their value as indicators of educational status and distort the educational process in undesirable ways. (Similar biases of course surround the use of objective tests in courses or as entrance examinations.)”

Campbell’s Law helps us understand why No Child Left Behind and Race to the Top are harmful to education. They put pressure on teachers and principals and school districts and states to get higher and higher test scores. As we saw in Atlanta and in Washington, D.C., this kind of pressure may cause educators to betray their ethical duty by changing test scores. As we saw in New York state, this kind of pressure may cause a state education department to lower the passing mark on state tests so as to boost proficiency rates.

As high-stakes testing has become the main driver of our nation’s education policy, we will see more cheating, more narrowing of the curriculum, more gaming of the system. None of this produces better education. And even the test scores–on which so much public policy now firmly rests–will be corrupted, by making them so important.