1.7 The outcomes are clearly defined.
1.8 The assessment of outcome is made blind to exposure status. If the study is retrospective this may not be applicable.
1.9 Where blinding was not possible, there is some recognition that knowledge of exposure status could have influenced the assessment of outcome.
1.10 The method of assessment of exposure is reliable.
1.11 Evidence from other sources is used to demonstrate that the method of outcome assessment is valid and reliable.
1.12 Exposure level or prognostic factor is assessed more than once.