Discard all questionable data, use the remaining data, and retrain the staff.
Discarding all questionable data is a somewhat costly but necessary decision.
These are some possible outcomes:
The loss of data from the data collection errors is minimal, and fortunately does not hinder the investigation. A meeting of the trainers is called to discuss how to improve current training procedures.
The loss of data does cause moderate concern among the investigators, somewhat limiting the investigation of the drug's efficacy. A meeting of the trainers is called to discuss how to improve current training procedures.
The loss of data significant, and compromises the investigation. Investigators must decide how to proceed with this situation. In addition, a meeting of the trainers is called to discuss how to improve current training procedures.