Are certain recommendation letters deemed more effective for the application?
A letter that addresses recollections of favorable personal interactions in a classroom or a laboratory setting is very valuable. Letters from professors in the student’s department who have direct experience with the student and can clearly compare him/her to others in this class or prior classes are effective. Also, letters from research supervisors in the student’s chosen area are important. Research-oriented letters are encouraged for those applying at the Ph.D. level.