Before revision:  I show that the identified set for these parameters given the information provided by the study and by various institutional details of the setting can be constructed using a linear programming method. Applying the developed analysis, I find that a significant proportion of children voluntarily enroll into Head Start if provided access and that Head Start is effective in terms of improving short-term test scoresacross multiple policy dimensions .
After revision:  I show that the identified set for parameters evaluating the average effects of program access in this model. I illustrate the framework by analyzing the average effects of Head Start preschool access using the Head Start Impact Study. I find that a significant proportion of children voluntarily enroll into Head Start if provided access and that Head Start is effective in terms of improving short-term test scoresacross multiple policy dimensions .