  Spreadsheets are widely used in industry, even for critical business
processes. This implies the need for proper risk assessment in spreadsheets to
evaluate the reliability and validity of the spreadsheet's outcome. As related
research has shown, the risk of spreadsheet errors is strongly related to the
spreadsheet's complexity. Therefore, spreadsheet researchers proposed various
metrics for quantifying different aspects of a spreadsheet in order to assess
its complexity. However, until now there is no shared understanding of
potential complexity drivers for spreadsheets. The present work addresses this
research gap by proposing a conceptual model integrating all aspects which are
identified by related literature as potential drivers to spreadsheet
complexity. In this sense, this model forms the foundation for a structured
definition of complexity metrics, and thus enhances the reproducibility of
their results. At the same time, it forms the foundation for identifying
further applicable complexity metrics from other scientific domains.
