Table 5.

Extracted from OHAT/NTP RoB tool (source: OHAT Handbook – 9 January 2015)b

Bias Domains and Questions	Controlled interventiona	Observational
Selection Bias
1. Was administered dose or exposure level adequately randomized?	X
2. Was allocation to study groups adequately concealed?	X
3. Did selection of study participants result in appropriate comparison groups?		X
Confounding Bias
4. Did the study design or analysis account for important confounding and modifying variables?		X
Performance Bias
5. Were the research personnel and human subjects blinded to the study group during the study?	X
Attrition/Exclusion Bias
6. Were outcome data complete without attrition or exclusion from analysis?	X	X
Detection Bias
7. Can we be confident in the exposure characterization?	X	X
8. Can we be confident in the outcome assessment?	X	X
Selective Reporting Bias
9. Were all measured endpoints reported?	X	X
Other Sources of Bias
10. Were there no other potential threats to internal validity (e.g., statistical methods were appropriate and researchers adhered to the study protocol)?	X	X

^aIncludes studies in humans with a controlled exposure including randomised controlled trials and non‐randomised intervention studies.

^b https://ntp.niehs.nih.gov/ntp/ohat/pubs/handbookjan2015_508.pdf