Amy Yvette Garrou, College admissions expert (US and international colleges)
This is a fascinating and multi-layered question. The assumption that colleges that are more selective provide students a better education begins with the glorification of the selectivity (what percentage of students who apply are accepted? Is it 5%, 25%, 60%, or 85%) instead of the quality of instruction and the success of its graduates. In other words, this assumption is built on inputs, rather than outcomes.
Both are important, no doubt. Many colleges correlate success in classes with an incoming student's grades in a highly rigorous high-school curriculum. If you made As and Bs in Honors and college-level classes such as Advanced Placement or International Baccalaureate courses, you are likely to continue to do so in college. It's common sense that a student needs to be prepared academically to handle both the challenge of heightened expectations for reading, writing, and quantitative ability as well as -- in most traditional campuses -- the ability to live and attend class in close quarters with others. Admissions offices' expectations of some level of student preparedness makes sense.
In some instances-- the most publicized ones--the supply of highly-qualified and accomplished applicants far outpaces the demand: at a large university, there may be 2500 dormitory beds, for example, and 40,000 applications for those 2500 freshman spots. At smaller liberal-arts colleges, there may be 400 freshman beds and 5,000 applications.
This may not be the place for a thorough discussion for the reasons behind the supply-and-demand disconnect at the nation's most selective institutions. For now, a few factors contributing to this are:
Size; Specialization and well-known departments; Age; History; Media attention, generated by successful sports teams or faculty in the news; "Brand" (an amalgamation of all the above factors, distilled into a logo or slogan or widespread marketing); Alumni loyalty.
We assume that the more selective an institution is, the "better" the education one receives. But what makes a "good" education? What makes a "good" college?
The answer may be different for each person. For someone who likes discussion-based classes (which are usually small, i.e. 30 or fewer students), going to a college or university where three of their five freshman and sophomore classes are taught as lectures three times a week with one hour of a small-group discussion may not constitute a "good" education, no matter how experienced the professor. Or a college (large or small) where eighty percent of a student's final grade is a result of one final exam could be the opposite way a particular student succeeds.
Having been a college counselor at three high schools, I've seen that most students don't factor the way they learn into their choice of colleges. They, or their families, go for a highly selective or famous school no matter that they've thrived in small high-school classes. Even if that student happens to be accepted by a college with an 8% acceptance rate, she may come back after the first year having struggled in order to make B's, or Cs, on those crucial final exams. She may have found it difficult to learn the material presented in a lecture format.
There are many other factors that can make one college "better" than another for a particular student (size, composition of the student body, attitudes and prevailing beliefs among the student body, activities available, living arrangements, even the weather).
Consider this example:
I had a student recently who applied to eight or ten colleges with single-digit acceptance rates. He applied to others with higher acceptance rates, even to a few who accept more than half of their applicant overall.
He wanted to study engineering or computer science. Although that's what he wanted, a few of his low-acceptance-rate colleges were not known as having the nation's best-resourced schools of engineering. They have terrific faculty and resources overall, but not necessarily the most emphasis on what he wanted to study.
In the end, he was accepted to the engineering honors program at our flagship state university (accepting some 45%), and to another large public university in another state accepting about 60% overall but whose engineering school is widely considered one of the best in the country, with large and varied engineering disciplines, sought-after professors, and state-of-the-art labs and research accessible to undergraduates. And, unlike another, similarly well-resourced university (with a 20% offer rate) where he got in, he could get into the computer science department as a freshman at the school with the 60% acceptance rate. He visited campus, he came back impressed, and he marveled to me at how a college with a high acceptance rate could be so "good." It was good for him: it allowed him to study what he wanted right away, and to be flexible if he decided to switch engineering majors; it had professors famous in their disciplines, and he liked the campus atmosphere, in particular the excitement he felt in the students and the faculty by the level of research being done.
It may seem logical, on the surface, to assume that colleges with low acceptance rates are "better," but going to college in the US offers such a wide variety of learning atmospheres, specializations, and campus atmospheres--taught by faculty who have been through a highly rigorous selection process themselves-- that it's a false generalization to equate a low acceptance rate with a better education.