[Mod: The late Dr Siff noted:

Many of us who have worked in several fields including neuropsychology 
and psychoneuroimmunology have witnessed similar changes in response to 
various shamanic, psychological, NLP, placebo and touch therapeutic methods. 
In fact it is very  rare to find ANY therapeutic systems which DO NOT enjoy a 
level  of success at some time or another which is more than sufficient to 
ensure a regular clientele, whether the method is virtually  witchcraft or 
not.  Apparently a success rate of less than 40 percent is quite adequate to 
ensure that a given therapist maintains a successful practice.  By all means 
state that certain methods may work in certain situations, but don't presume 
that they do so for  scientific reasons which have never been proved.]