Residency after 40 is about 40 times tougher.
Berger
M B
MB
D000367:Age Factors; D002322:Career Mobility; D005257:Fellowships and Scholarships; D006405:Hematology / Q000193:education*; D006801:Humans; D007396:Internship and Residency; D008495:Medical Oncology / Q000193:education*; D008875:Middle Aged; D010820:Physicians / Q000523:psychology*; D011216:Practice Management, Medical