** ReadMe_QOB.txt ** This folder contains the data and programs used to generate Tables 6.4 and 6.5 and Figures 6.1 and 6.2 in Mastering Metrics. These tables and figures present an IV analysis of the returns to schooling using quarters of birth (QOB) as instruments for years of schooling. The same analysis appears in Angrist and Krueger (QJE 1991). Data: * ak91.dta Code: * /QOB/Code/ak91.do Output: * /QOB/Output/Table64.xls (Table 6.4) * /QOB/Output/Table65.xls (Table 6.5) * /QOB/Output/fig61_first.png (Figure 6.1) * /QOB/Output/fig62_reduced.png (Figure 6.2)