A similar study by Gould, Dixon, Najdowski, Smith and Tarbox in 2011 compares 30 assessments, including the ABLLS-R , Bayley, Brigance ... and the VB-MAPP. The authors reviewed the 30 assessments for: comprehension, targets child development, considers behavior function and not just topography, link from the assessment to curricula targets and useful for tracking child progress over time. The authors concluded: "After reviewing the assessments described above, only four meet our five criteria most closely: the VB-MAPP, Brigance IED-II, VABSII and CIBS-R." 
Some studies offer partial support for the test publishers' claims. For example, several studies concluded that for admissions tests, coaching produces only modest, if statistically significant, score gains.   Other studies, and claims by companies in the preparation business were more positive.  Other research has shown that students score higher with tutoring, with practice using cognitive and metacognitive strategies and under certain test parameters, such as when allowed to review answers before final submission, something that most computer adaptive tests do not allow.