  The digital economy is a highly relevant item on the European Union's policy
agenda. Cross-border internet purchases are part of the digital economy, but
their total value can currently not be accurately measured or estimated.
Traditional approaches based on consumer surveys or business surveys are shown
to be inadequate for this purpose, due to language bias and sampling issues,
respectively. We address both problems by proposing a novel approach based on
supply-side data, namely tax returns. The proposed data-driven record-linkage
techniques and machine learning algorithms utilize two additional open data
sources: European business registers and internet data. Our main finding is
that the value of total cross-border internet purchases within the European
Union by Dutch consumers was over EUR 1.3 billion in 2016. This is more than 6
times as high as current estimates. Our finding motivates the implementation of
the proposed methodology in other EU member states. Ultimately, it could lead
to more accurate estimates of cross-border internet purchases within the entire
European Union.
