Table 6.

An overview of Study 2.

Phase	Task	Responsible
Plan	Define inclusion criteria for Delphi participants (expert panellists).	Project group
	Nominate and recruit expert panellists fulfilling the inclusion criteria. Create the questionnaire addressing the bias domains and items relevant for in vitro studies identified in Study 1.	Project group and scientific advisory group
Actions	Delphi round 1  Expert panellists complete the questionnaire and have the possibility to suggest additional bias domains and items. Between Delphi rounds 1 and 2  Analyse results from round 1.  Feedback from round 1 is given to the expert panellists.  Bias domains and items that met criteria for identification of agreement for inclusion in INVITES-IN are removed.  Bias domains and items that met criteria for identification of agreement for exclusion from INVITES-IN are removed.  New questions may be included, and existing questions may be revised. Delphi round 2  Feedback from round 1 is given to the expert panellists.  Expert panellists complete the questionnaire.  Analyse results from round 2.	Project group
	Workshop  Expert panellists will be guided through a discussion of uncertainties related to bias domains and items for which agreement for inclusion or exclusion is not identified.  Prepare transcripts, organise and summarise results.	Project group
Result	Expert agreement on bias domains and items of importance for internal validity of in vitro studies is identified.	Project group