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Table 2 Risk of bias assessment tool (adapted from the Risk of Bias Tool for Prevalence Studies developed by Hoy et al. [24])

From: Prevalence, predictors and adverse outcomes of adolescent pregnancy in sub-Saharan Africa: a protocol of a systematic review

Risk of bias item Response: Yes (Low Risk) or No (High risk)
External Validity
 1. Was the study target population a close representation of the national population in relation to relevant variables?  
 2. Was the sampling frame a true or close representation of the target population?  
 3. Was some form of random selection used to select the sample, OR, was a census undertaken?  
 4. Was the likelihood of non-participation bias minimal?  
Internal Validity
 5. Were data collected directly from the subjects (as opposed to medical records)?  
 6. Was an acceptable case definition used in the study?  
 7. Was the study instrument that measured the parameter of interest (e.g. prevalence of adolescent pregnancy) shown to have reliability and validity (if necessary)?  
 8. Was the same mode of data collection used for all subjects?  
 9. Was the length of the shortest prevalence period for the parameter of interest appropriate?  
 10. Were the numerator(s) and denominator(s) for the calculation of the prevalence of adolescent pregnancy appropriate?  
 11. Summary item on the overall risk of study bias
Low Risk of Bias: 8 or more “yes” answers. Further research is very unlikely to change our confidence in the estimate.
Moderate Risk of Bias: 6 to 7 “yes” answers. Further research is likely to have an important impact on our confidence in the estimate and may change the estimate.
High Risk of Bias: 5 or fewer “yes” answers. Further research is very likely to have an important impact on our confidence in the estimate and is likely to change the estimate