Thanks Maha for pointing me back to this interesting discussion. There are different levels of anonymity. Researchers who interview participants will almost know their identity and something about their background but may anonymise the interview content by mutual agreement with the participants. There are issues that people won’t raise without anonymity eg in organisation-based research and there are aspects that remain unresearched for reasons of identity and power eg http://www.psychotherapybrownbag.com/psychotherapy_brown_bag_a/2009/04/making-things-worse-through-treatment-iatrogenic-psychological-interventions.html