A school voucher, also called an education voucher, in a voucher system, is a certificate of government funding for a student at a school chosen by the student or the student's parents. The funding is usually for a particular year, term or semester. In some countries, states or local jurisdictions, the voucher can be used to cover or reimburse home schooling expenses. In some countries, vouchers only exist for tuition at private schools. According to a 2017 review of the economics literature on school vouchers, "the evidence to date is not sufficient to warrant recommending that vouchers be adopted on a widespread basis; however, multiple positive findings support continued exploration." A 2006 survey of members of American Economic Association found that over two-thirds of economists support giving parents educational vouchers that can be used at government-operated or privately operated schools, and that support is greater if the vouchers are to be used by parents with low-incomes or parents with children in poorly performing schools.