Create a tool for evaluation of internal validity of in vitro studies

Internal validity is the extent to which a study is free from bias, where bias is systematic error, or deviation from the truth.

We aim to address this situation by developing a new tool for evaluating the internal validity of in vitro studies. We will build on prior work and use rigorous methods consistent with our intent to provide an authoritative assessment tool.

Four studies will be performed to create the release version of this tool. In the first study, evaluation of existing assessment tools will be combined with focus group discussions to identify how characteristics of the design or conduct of an in vitro study can affect its internal validity. In the second study, group agreement on internal validity domains and items of importance for in vitro studies will be identified via a modified Delphi methodology. In the third study, the draft version of the tool will be created. The fourth study will be performed to validate the tool and to collect users’ experience.

Expected deliveries:


  • Creation of the tool (submitted)
  • User testing (in progress)

Creation of the tool

  • Evaluation the relevance of the internal validity items for in vitro studies (in progress)
  • Ranking internal validity items according to importance for in vitro studies
  • The draft tool
  • The user testing and validation of the draft tool

The release version of the tool