Members of some religions hosting their own private schools for indoctrination purposes may desire having general public subsidization of their separate private efforts from money otherwise going into public education. Some might think it a good idea, others might favor not beggaring public education. Outlooks vary.
In Minnesota statewide Republican candidates, and some legislative candidates want vouchers. Catholic candidates in particular, where private Catholic schools have existed apart from public education for decades; likely since before the founding of the nation.
IN THAT CONTEXT: Looking at the headlined statement, a quick and simple websearch = correlation vouchers "test scores"
It is clearly a simplistic first cut at seeing what credible study may have been done and what it says about the wisdom or lack of wisdom in implementation of vouchers (where often "parental choice" is used as a politically loaded term for voucher implementation).
Readers are urged from that single search basis to do their own further more sophisticated web searching to satisfy their minds whether they can find if any even quasi-determinative objective data exists on the Internet, about the question.
From that beginning seach, things are inconclusive, as should be expected; with relevant return items (one a study by advocates of vouchers) here, here and here.
The paucity of results before returned links get further and further from the intended returns was a surprise. Apparently there is not much good data, and of the three items listed, the last was by Heritage Foundation, which is not objectively apolitical.
BOTTOM LINE: If anyone wants to sell you on vouchers, or against vouchers, demand they rest opinions on data, or if not demand they be clear and specific about what their opinions rest upon; or seek better advice from better advisors without skin in the game one way or the other.
Catholics touting vouchers should be viewed as having skin in the game, not being subsidized by all of us without vouchers while being subsidized under private voucher programs, so that transparency of disclosure - conflicting interests, if any - is important to pin down.
Last, politicians touting "parental choice" without spelling out wtf they mean by such an obscenely elastic term should be distrusted as playing more to emotions than in favor of any real objectivity.
What you'd want from an honest politician (an oxymoron?) is the whole truth, not quick loaded words -briefly spun - which might sound resonant at the moment, but in fact be nothing but empty manipulation of some words with no substance behind them. Be a skeptic. Do not presume what a politician is saying is the same as what you might find reasonable in one sense but not in others. Pin things down.