EXHIBIT 2 Vouching for Vouchers Voucher Controversy Title: Author: Source: White House Ignores Evidence of How D.C. School Vouchers Work Editorial Board Opinion Washington Post, March 29, 2011, http://www.washingtonpost.com/opinions/ white-house-ignores-evidence-of-how-dc-school-vouchers-work/2011/03/29/ AFFsnHyB_story.html Consider the following statements from a recent Washington Post editorial discussing the Obama strongly worded dismissal of school vouchers. The article says: That dismissal might come as a surprise to Patrick J. Wolf, the principal investigator who helped conduct the rigorous studies of the D.C. Opportunity Scholarship Program and who has more than a decade of experience evaluating school choice programs. Here's what Mr. Wolf had to say about the program in Feb. 16 testimony to the Senate Committee on Homeland Security and Governmental Operations. "In my opinion, by demonstrating statistically significant experimental impacts on boosting high school graduation rates and generating a wealth of evidence suggesting that students also benefited in reading achievement, the DC OSP has accomplished what few educational interventions can claim: It markedly improved important education outcomes for low-income inner-city students." Questions 1. The phrase "statistically significant" is used in Mr. Wolf's testimony. Define the parameters of interest and state the null and alternative hypothesis. 2. What do we know about the p-value compared to alpha? Which Type of error could we be making?