The British doctor Richard Asher noted in one of his essays for doctors:
‘If you can believe fervently in your treatment, even though controlled tests show that it is quite useless, then your results are much better, your patients are much better, and your income is much better, too. I believe this accounts for the remarkable success of some of the less gifted, but more credulous members of our profession, and also for the violent dislike of statistics and controlled tests which fashionable and successful doctors are accustomed to display.’Asher R. Talking sense (Lettsomian lecture, 16 Feb, 1959). Transactions of the Medical Society of London, vol LXXV, 1958-59. Reproduced in: Jones, FA, ed. Richard Asher talking sense. London: Pitman Medical, 1972.
This is why so many IVF doctors continue offering "immune therapy" such as IV Ig for patients with high NK cells and repeated IVF failure !