My understanding is that the "placebo effect" doesn't refer to biased numbers or reporting, but exists when everything is measured correctly. It is objectively there, not a screwy result.
- http://www.socialresearchmethods.net/kb/relandval.php
- http://www.mathcs.duq.edu/~packer/Courses/Psy624/Validity.ht...
But basically, the placebo effect only exists for subjective measurements. (http://en.wikipedia.org/wiki/Placebo#Mechanism_of_the_effect) If something exists only in subjective measurements and not objective measurements... I'll let you draw your own inference.