We have used STAR Math by Renaissance Learning for several years. We find it does a nice job determining skill deficiency. However, the rigor of the assessment is not to the level of the FORWARD exam. Their is a very strong correlation between the two assessments. That is, if a student does poorly on STAR they will on FORWARD also. However, if they do well they don't always do well on the FORWARD.
Have other districts done the correlations to determine success of screeners and their correlations and found strong results. If yes, what screeners do you use?
I've read the book and really enjoyed Google it.