They argue that in the Chilean system (where schools can select students based on ability), the schools are more likely to compete by selecting the best students instead of with increasing productivity.

FORBES: Lessons on School Choice from Sweden

Stuyvesant is widely regarded as the best of the nine free New York City public high schools that select students based on a highly competitive Specialized High Schools Admissions Test (SHSAT).

FORBES: Stuyvesant High School Has A Cheating Problem. Here's How To Fix It

Some students even select their school on the basis of the uniform.

CNN: A SOCK TO THE SYSTEM

As universities select applicants on academic merit, less well-qualified Scottish students might be squeezed out and have to go to fee-charging English universities.

ECONOMIST: Tuition fees