Problems of Moral Hazard in Health Insurance

Studies that identify the effect of a voucher program on the student achievement of those who use vouchers typically do so by comparing the achievement of students who used the voucher to switch to a different school to the achievement of otherwise similar students who wanted to but could not use the voucher to switch to a different school. Will such studies capture the effects of increased competition on the inefficient schools in the voucher-eligible area? Explain.