Paul E. Peterson and Matthew Chingos have released a study analyzing the results of a 1997 New York city voucher experiment:
Overall, we find no significant effects of the offer of a school voucher on college enrollment. However, we find evidence of large, significant impacts on African Americans, and fairly small but statistically insignificant impacts on Hispanic students. A voucher offer is shown to have increased the overall (parttime and full-time) enrollment rate of African Americans by 7.1 percentage points, an increase of 20 percent. If the offered scholarship was actually used to attend private school, the impact on African American college enrollment is estimated to be 8.7 percentage points, a 24 percent increase.
Peterson and Chingos offer a number of hypotheses regarding the stark difference in the impact of vouchers on black vs. Hispanic students, e.g.:
We find suggestive evidence that educational and religious reasons may explain the different findings for African American and Hispanic students. Although it would be incorrect to say that educational objectives were not uppermost in the minds of respondents from both ethnic groups (as respondents from both groups made it clear that such was the case), the weight given different objectives appears to have differed in some respects. African American students were especially at risk of not going on to college, and families sought a private school—even one outside their religious tradition—that would help their child overcome that disadvantage. Hispanic students were less at risk of not enrolling in college and likely sought a voucher for some combination of religious and educational benefits.
It is worth remembering that New York city’s black and Hispanic populations are very diverse, and that its Hispanic population is far more Caribbean than the U.S. Hispanic population as a whole. Results that obtain in New York city might not apply elsewhere.