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Chapter 8:  Assessing risk of bias in included studies

Editors: Julian PT Higgins, Douglas G Altman and Jonathan AC Sterne on behalf of the Cochrane Statistical Methods Group and the Cochrane Bias Methods Group.


Key points


8.1 Introduction

8.2 What is bias?

8.3 Tools for assessing quality and risk of bias

8.4 Introduction to sources of bias in clinical trials

Table 8.4.a: A common classification scheme for bias

8.5 The Cochrane Collaboration’s tool for assessing risk of bias

8.6 Presentation of assessments of risk of bias

Figure 8.6.a: Example of a ‘Risk of bias’ table

Figure 8.6.b: Example of a ‘Risk of bias graph’ Figure

Figure 8.6.c: Example of a ‘Risk of bias summary’ Figure

8.7 Summary assessments of risk of bias

Table 8.7.a: Possible approach for summary assessments

8.8 Incorporating assessments into analyses

8.9 Sequence generation

8.10 Allocation sequence concealment

8.11 Blinding of participants and personnel

8.12 Blinding of outcome assessment

8.13 Incomplete outcome data

8.14 Selective outcome reporting

8.15 Other potential threats to validity

8.16 Chapter information

8.17 References