Catholic high schools in the United States have long boasted a 99 percent graduation rate compared to 73 percent for public schools, and they report sending twice as many students to four-year colleges.
Now, an education study from Michigan State University system's Oakland University finds there may be a substantial cash benefit for those who obtain a Catholic high school degree. On average, it shows, students who graduated in 1957 from Catholic high schools earned 18 percent higher wages in their mid-30s and mid-50s than their peers in public high schools.
It's true that Catholic students tend to have higher IQs and more educated and affluent parents than students in public schools, said researcher Young-Joo Kim, a former assistant professor of education at Oakland. But even taking into account those differences, she said, Catholic high school graduates still earned 10 percent more than their peers in public schools.
What was the secret of their success? The biggest difference, Kim found, is that the Catholic high school students took more math classes and more language classes and had more highly educated and experienced teachers.
"Most of the Catholic school effects are explained by these school quality measures," she said. "Having more educated teachers and taking more math courses in high school are rewarded in the labor market," factors that likely are just as valid in 2011 as in 1957.
More than half of the Catholic high school teachers had master's degrees, and some had also earned a doctoral degree or multiple bachelor's degrees. They pursued educational advancement throughout their careers by attending summer classes or taking courses between jobs. By contrast, Kim found, only 27 percent of public school teachers had more than a bachelor's degree.
While some recent studies have suggested that teaching skills are not linked to more experience or higher degrees, Kim shows the opposite is true. In 1957, Catholic high school classes were largely taught by nuns, many of whom had started out in elementary school. Counting those years, they had four times more teaching experience than public high school teachers.
(And salary was not a factor, Kim found. The sisters received only a small stipend for their work from the Catholic Church, a flat amount — $50 per month in Milwaukee — regardless of their schooling or experience. By contrast, public school teachers were earning $335 monthly, on average, in 1957.)
Back then, Catholic education was at its peak in the United States. Four hundred of the 3,500 high school graduates in Kim's sample, or 11 percent, attended neighborhood Catholic schools. Nationwide, more than 8 percent of high school students attended Catholic schools. The 3,500 students in Kim's sample, most of them white males, were taken from a much larger long-term study of Wisconsin high school graduates who were randomly selected in 1957. The Wisconsin study provided data on public high school teachers and school quality; and Kim consulted Catholic school directories and reports as well.
Curriculum made a big difference, she found. Catholic students took a wider range of math courses and more of them — about six semesters — compared to fewer than five semesters for public high school students. One semester of algebra taken in high school translated to 4 percent higher wages, 17 years after graduation, and about 6 percent higher wages after 36 years, Kim found.
In addition, Catholic high school students took more language courses — eight semesters of English, for example, while more than 25 percent of public school students took fewer than eight semesters. Ninety percent of Catholic high school students took at least two semesters of a foreign language, too, and more than 25 percent took eight semesters. By contrast, more than half of students in public high schools took no foreign language courses at all, and only the top 1 percent took eight semesters.
Perhaps the wage gap can be explained in part by a college education, Kim said: Proficiency in math and a foreign language makes a difference when high school seniors apply to college. On average, she found, the Catholic school students completed one more year of college than their peers from public schools.
Kim notes that her study shows much larger impacts of teacher education than some research with more recent data in the field. That's because many more public high school teachers have advanced degrees today than they did in the 1950s, she said.
"Yet considering that some of the key components of Catholic school effects are still prominent features of contemporary Catholic schools," Kim said, "one might expect the positive effects of Catholic school on wages documented in this study to persist until today."