A note on methodology: best colleges for adult learners.

We began with the 7,687 postsecondary institutions listed in the Integrated Postsecondary Education Data System (IPEDS) as being active in the 2014-15 academic year. We then limited the sample to all colleges with a Carnegie basic classification in 2015 of between 1 and 23, excluding many certificate-granting institutions as well as special-focus institutions such as medical schools or rabbinical programs. We dropped fifty-eight colleges for being outside the fifty states and Washington, D.C., dropped seven colleges for closing or merging since 2014-15, dropped four colleges for not participating in any federal financial aid programs, and dropped the five service academies to be consistent with the main rankings. An additional 130 colleges were excluded for having fewer than 100 students in any of the last three years in which they were open.

The next sample restriction was to exclude colleges that did not have data on all of the outcome measures. Another 513 colleges were dropped for not participating in the College Board's Annual Survey of Colleges, which is key in our rankings. Fifteen colleges did not have data on the percent of adult students, 315 colleges did not have data on average earnings of independent students, and we excluded 808 colleges that participated in the federal student loan program but did not report a separate repayment rate for independent students. As we used the percentage of adult students as one of our metrics, colleges with insufficient numbers of independent students to have a separate repayment rate for independent students were unlikely to score highly in this ranking anyway. For twenty colleges that served at least 75 percent adult students and did not have separate data on earnings or repayment rates for independent students, we instead used data for all students. Our resulting sample is 1,749 colleges, of which 571 are considered four-year colleges (based on Carnegie classification and whether they awarded more bachelor's degrees than certificates or associate's degrees) and 1,178 are two-year colleges. As a final precaution to weed out especially questionable colleges, we crosschecked all our rankings with the Department of Education's level-two heightened Cash Monitoring List. We then randomly selected five schools on each of the two lists, checked their status on the less severe level-one Heightened Cash Monitoring List, verified their accreditation, and searched through local and national news clips...