The objective of the virk.dk project at Statistics Denmark is to develop electronic web questionnaires to replace paper and pencil questionnaires in data collection for business statistics. In the present phase of the project we introduce web based selfcompletion questionnaires as an alternative to the existing paper and pencil questionnaires. And for some time to come, the new electronic mode of data collection will exist alongside the paper mode. Thus respondents will be allowed to choose between the two modes.

The quest for valid data, high response rates and minimal response burden calls for task facilitating e-functionalities and design which is optimised to the mode of actual use. But the quest for reliable data across modes calls for maximum equivalence and similarity between the electronic and paper mode.

We will present and discus examples, findings and guidelines from the virk.dk project with regard to striking a balance between accomplishing user friendliness in electronic questionnaires and minimising mode effects in the mixed mode data collection.

Electronic questionnaires offer new dynamic and user-friendly functionalities, which may assist respondents in completing tasks and thus improve data quality. Dynamic functionalities, such as auto calculation, routing and concurrent data validation, are commonly used in other kinds of electronic forms. Thus respondents may expect them in electronic questionnaires. And this expectation may imply a decrease in respondents own focus and effort with regard to routing, calculation and internal consistency when completing electronic questionnaires.