Applying ED/EA/REA/SCEA… offers a benefit at many highly selective colleges, but not all highly selective colleges. The degree of that benefit varies from one college to the next. I’d expect that colleges that are big on “demonstrated interest” often have a greater ED benefit than many “elite” colleges. For example, Lehigh marks level of interest at the same importance as test scores in their CDS and as discussed in the article at http://articles.philly.com/2013-04-01/news/38165511_1_admissions-placement-courses-high-school-students , goes so far as to significantly penalize students for not logging in to their online portal to check application status. Colleges that are considered “elite” rarely go this far and often say they don’t consider demonstrated interest at all in their CDS. However, there is still often a notable benefit to applying early at many “elite” colleges.
The study at https://web.stanford.edu/~jdlevin/Papers/EarlyAdmissions.pdf reviewed early decision at a list of “elite” colleges. It concludes that after controlling for SAT score, demographics, quality of ECs, and other factors, '“An early action application is associated with a 17 to 20 percentage point increase in admission probability, and an early decision application with a 31 to 37 percentage point increase.” An older study of hundreds of thousands applicants to “elite” colleges estimated an average increase in chance of admission by 25% after controlling for applicants with similar hook factors, SAT score, high school GPA, and others. However, the benefit was highly variable, with no benefit at certain schools.
In the Harvard lawsuit analysis, both the Plantiff and Harvard’s internal studies found that applying REA offered a benefit for unhooked applicants at Harvard. The degree of that benefit was smaller than traditional hooks like recruited athlete, URM, or legacy; but was still noteworthy. Specific regression coefficients are below, after controlling for hooks and various other factors. The larger the number, the bigger the associated impact on chance of admission.
Athlete: +7.85 (2500x increase in odds of admission)
Dean’s Special Interest List: +2.32 (10x increase in odds of admission)
Legacy: +1.84 (6x increase in odds of admission)
Children of Faculty/Staff: +1.70 (5x increase in odds of admission)
**Applies Early: +1.28/b
Academic Rating Increases from 3 to 2: +0.84 (2x increase in odds of admission… associated with increase from “respectable” to “excellent” grades combined with 100-200 point increase on SAT)