I've been studying charter schooling lately. One thing that charter schools feel the need to do is prove their worth by showing that student achievement is higher at their schools. Some studies have confirmed their efficacy. Some have not. Proponents of charter schooling have called many of these contradictory studies into question based on their means of comparison. For example, if a charter school has a greater number of minority students than the comparison school, then it's hard to compare test results. As we've seen in other readings, minority test scores are lower, overall.
So, one problem with testing and research is that people rarely agree on the results. Testing, in many ways, can highlight our disagreements and make dissenters even more obdurate to change. In America, we often agree to disagree. That's why we have alternative forms of schooling in the first place.