Assessment- Measurement of outcomes or endpoints in the study and control groups

1. Appropriate
Does the measurement of outcomes address the study's question?

2. Accurate and precise
Is the measurement of outcomes an accurate and precise measure of the phenomenon that the investigators seek to assess?

3. Complete and unaffected by observation
Is the follow-up of participants nearly 100% complete and is it affected by the participants' or the investigators' knowledge of the study or control group assignment?