PURPOSE: In the migration of paper-based patient-reported outcome (PRO) measures to electronic data collection modes (e.g., smartphone or tablet computer), there has long been a concern about the introduction of bias into the data collected from the electronically migrated questionnaire.  This workshop, conducted by representatives of the ePRO Consortium, will provide participants with an overview of equivalence testing methodology, a summary of the results of the equivalence testing that has been conducted to date, and insight into the need to continue testing paper versus electronic versions of questionnaires. DESCRIPTION: When migrating paper-based instruments to electronic modes of data collection, equivalence testing has been recommended to assess whether the respondents interpret and respond the same way to a questionnaire’s items regardless of the data collection mode.  This can include qualitative evaluation, via cognitive interviewing and usability testing, and quantitative testing, based on the statistical comparison of respondents’ answers across modes.  Participants will be provided a brief introduction to electronic capture of PRO data, the concerns over response bias between paper and electronic versions of questionnaires, and the different ways potential bias can be examined through qualitative and quantitative equivalence testing.  A summary of the existing measurement equivalence evidence between various modes of administration will also be provided.  Outstanding questions and concerns about the risks of implementing paper-based questionnaires electronically will be discussed, particularly in light of the growing interest in “bring your own device” (BYOD) methodologies.  All discussion leaders will present their views regarding the ongoing need for equivalence testing in the rapidly evolving field of electronic data capture and will encourage participants to share their experiences and perspectives during the workshop.  In addition, workshop participants will be asked to compare various scenarios of paper to electronic migrations to identify potential sources of bias and discuss the need for equivalence testing.