Importantly, those teachers whose scores were determined (at least in part) on the basis of empirical measures of student growth had more score variation (54 percent receiving «Exceeds») than those assessed via growth goals based on professional standards (69 percent receiving «Exceeds»). (educationnext.org)
The state didn't include in the report data from empirical measures of student growth (SGPs in this case), though they say that it is coming. (educationnext.org)
As a result, its existence can't be incontrovertibly demonstrated or disproved by empirical measures. (discovermagazine.com)