The study notes that, according to the Department of Education's most recent study, 19 percent of undergrads at four-year colleges received merit aid despite scoring under 700 on the SAT. Their only merit, in some cases, might well have been mom and dad's bank account.
The study doesn't actually say that, at least not according to the chart on page 4. It says that 18.8% of the students in college who had scores of 0-699 got merit aid. Not that 18.8% of all the students in college received aid with such low scores.