How double blind is double blind? And does it matter?

In an apparently double blind crossover study, two experienced measurement technicians were able to identify many of the treatment periods. They most often correctly identified aspirin, a drug with prominent effects and side effects. It is argued that in many circumstances it is better to use a blind observer who is not concerned with the giving of treatment or the collection of side effects.

RCT Entities:   Population Interventions Outcomes