This is the executive summary of the statement of the American Statistical Association on the use of value-added assessment to evaluate teachers. Please share it with other teachers, with principals, and school board members. Please share it with your legislators and other elected officials. Send it to your local news outlets. The words are clear: Teachers account for between 1 and 14% of the variation in test scores. And this is very important to remember: “Ranking teachers by their VAM scores can have unintended consequences that reduce quality.”