Growth is estimated most accurately by procedures involving the pretest-posttest difference, and for practical purposes all estimates involving this difference have approximately equal accuracy. In particular, the simple difference between pretest and posttest scores seems about as accurate as any other estimate, easier to compute, and meaningful…

Recent research results strongly suggest that the theoretical problems of change measures have limited practical significance for measuring individual growth, and it is important to determine whether this is also the case for measuring school impact. Accordingly, in this study artifical data were used to assess the correlation between several…