I need it in next 6 hrs. paying $50 for it Instrumental variable methods Question page 5: We have the classic ability bias (what is the likely sign

I need it in next 6 hrs. paying $50 for it

Instrumental variable methods

Question page 5: We have the classic ability bias (what is the likely sign of the bias?)

Question page 6: How can we obtain an unbiased estimate of r if ability is unobserved?

Question page 10:

For instance: between 15 and 16 years old both will be in the same grade, but those born earlier can drop out of school because they already turn 16 while those born late, will need to go through one additional school year before being allowed to leave leaving. Do you think this IV satis.es the exclusion restriction?