One of the Carnegie Foundation’s six core principles of improvement is: “We cannot improve at scale what we cannot measure.” We know we must collect, interpret, and act on evidence by measuring the outcomes, processes, and even unintended consequences of our work. Otherwise, we cannot know what worked (or not) for whom; we cannot make changes to improve upon what we’ve learned. Yet we in the education field — experts, practitioners, and policymakers — often don’t agree on what counts as “evidence”.

In his book “Proof,” Policy, and Practice: Understanding the Role of Evidence in Improving Education, Paul E. Lingenfelter explores what is often a huge gulf between what researchers and practitioners consider to be “proof” of improvement in education. We can’t expect to find “crisp, scientific solutions to most tough human problems,” such as the complex system of education, he says. Instead, Lingenfelter argues for a more nuanced approach to using evidence to drive improvement, through which empirical qualitative and quantitative data can be understood and put to practical use.