Risk of bias requirements
When a study is entered into the HAWC database for use in an assessment, risk of bias metrics can be entered for a metric of bias for each study. Risk of Bias metrics are organized by domain. The following questions are required for evaluation for this assessment.
Requirements by Study Type
| Domain | Metric | Bioassay | Epidemiology | In Vitro |
|---|---|---|---|---|
| Selection2735 | Did selection of study participants result in appropriate comparison groups?4768 | - | ✔ | ✔ |
| Selection2735 | Was allocation to study groups adequately concealed?4767 | ✔ | - | ✔ |
| Selection2735 | Was administered dose or exposure level adequately randomized?4766 | ✔ | - | ✔ |
| Confounding2736 | Did the study design or analysis account for important confounding and modifying variables?4769 | - | ✔ | ✔ |
| Performance2737 | Were experimental conditions identical across study groups?4770 | ✔ | - | ✔ |
| Performance2737 | Were the research personnel and human subjects blinded to the study group during the study?4771 | ✔ | - | ✔ |
| Attrition2738 | Were outcome data complete with respect to attrition or exclusion from analysis?5570 | ✔ | ✔ | ✔ |
| Detection2739 | Can we be confident in the exposure characterization?4773 | ✔ | ✔ | ✔ |
| Detection2739 | Can we be confident in the outcome assessment?4774 | ✔ | ✔ | ✔ |
| Selective Reporting2740 | Were all measured outcomes reported?4775 | ✔ | ✔ | ✔ |
| Other2741 | Were there any other potential threats to internal validity?4776 | ✔ | ✔ | ✔ |
Selection2735
Was allocation to study groups adequately concealed?4767
Allocation concealment requires that research personnel do not know which administered dose or exposure level is assigned at the start of a study. Human studies also require that allocation be concealed from human subjects prior to entering the study.
Note:
- a question under performance bias addresses blinding of personnel and human subjects to treatment during the study;
- a question under detection bias addresses blinding of outcome assessors.
Was administered dose or exposure level adequately randomized?4766
Randomization requires that each human subject or animal had an equal chance of being assigned to any study group including controls (e.g., use of random number table or computer generated randomization).
Performance2737
Were experimental conditions identical across study groups?4770
Were the research personnel and human subjects blinded to the study group during the study?4771
Blinding requires that study scientists do not know which administered dose or exposure level the human subject or animal is being given (i.e., study group). Human studies also require blinding of the human subjects when possible.
Attrition2738
Were outcome data complete with respect to attrition or exclusion from analysis?5570
Attrition rates are required to be similar and uniformly low across groups with respect to withdrawal or exclusion from analysis
Detection2739
Can we be confident in the exposure characterization?4773
Confidence requires valid, reliable, and sensitive methods to measure exposure applied consistently across groups.
Can we be confident in the outcome assessment?4774
Confidence requires valid, reliable, and sensitive methods to assess the outcome and the methods should be applied consistently across groups.
Selective Reporting2740
Were all measured outcomes reported?4775
Other2741
Were there any other potential threats to internal validity?4776
On a project specific basis, additional questions for other potential threats to internal validity can be added and applied to study designs as appropriate.
Examples may include appropriateness of statistical methods, adherence to the study-protocol, etc.
Selection2735
Did selection of study participants result in appropriate comparison groups?4768
Comparison group appropriateness refers to having similar baseline characteristics between the groups aside from the exposures and outcomes under study.
Confounding2736
Did the study design or analysis account for important confounding and modifying variables?4769
Attrition2738
Were outcome data complete with respect to attrition or exclusion from analysis?5570
Attrition rates are required to be similar and uniformly low across groups with respect to withdrawal or exclusion from analysis
Detection2739
Can we be confident in the exposure characterization?4773
Confidence requires valid, reliable, and sensitive methods to measure exposure applied consistently across groups.
Can we be confident in the outcome assessment?4774
Confidence requires valid, reliable, and sensitive methods to assess the outcome and the methods should be applied consistently across groups.
Selective Reporting2740
Were all measured outcomes reported?4775
Other2741
Were there any other potential threats to internal validity?4776
On a project specific basis, additional questions for other potential threats to internal validity can be added and applied to study designs as appropriate.
Examples may include appropriateness of statistical methods, adherence to the study-protocol, etc.
Selection2735
Did selection of study participants result in appropriate comparison groups?4768
Comparison group appropriateness refers to having similar baseline characteristics between the groups aside from the exposures and outcomes under study.
Was allocation to study groups adequately concealed?4767
Allocation concealment requires that research personnel do not know which administered dose or exposure level is assigned at the start of a study. Human studies also require that allocation be concealed from human subjects prior to entering the study.
Note:
- a question under performance bias addresses blinding of personnel and human subjects to treatment during the study;
- a question under detection bias addresses blinding of outcome assessors.
Was administered dose or exposure level adequately randomized?4766
Randomization requires that each human subject or animal had an equal chance of being assigned to any study group including controls (e.g., use of random number table or computer generated randomization).
Confounding2736
Did the study design or analysis account for important confounding and modifying variables?4769
Performance2737
Were experimental conditions identical across study groups?4770
Were the research personnel and human subjects blinded to the study group during the study?4771
Blinding requires that study scientists do not know which administered dose or exposure level the human subject or animal is being given (i.e., study group). Human studies also require blinding of the human subjects when possible.
Attrition2738
Were outcome data complete with respect to attrition or exclusion from analysis?5570
Attrition rates are required to be similar and uniformly low across groups with respect to withdrawal or exclusion from analysis
Detection2739
Can we be confident in the exposure characterization?4773
Confidence requires valid, reliable, and sensitive methods to measure exposure applied consistently across groups.
Can we be confident in the outcome assessment?4774
Confidence requires valid, reliable, and sensitive methods to assess the outcome and the methods should be applied consistently across groups.
Selective Reporting2740
Were all measured outcomes reported?4775
Other2741
Were there any other potential threats to internal validity?4776
On a project specific basis, additional questions for other potential threats to internal validity can be added and applied to study designs as appropriate.
Examples may include appropriateness of statistical methods, adherence to the study-protocol, etc.