To be sure, statewide analyses can provide
accurate estimates of the impact of school resources — but only if the
analyst includes within the statistical model all the factors that affect student performance and, in the standard linear regression model generally favored by RAND, if these factors have a constant, additive effect on student achievement.
As the following
analyst scorecard indicates, when making 1 - year forward and 2 - year forward
estimates since calendar year 2000, the record of
analysts following Southern Company has been consistently
accurate at over 93 %.