Start-up complexity and the thickness of regional input markets

•We investigate the impact of input market thickness on regional start-up activity.•Regional determinants of high and low complexity start-ups differ substantially.•Population, employment and investment density are conducive to start-ups in general.•Complex start-ups are pushed by a high density of human capital and R&D.

Start-ups in different industry groups are classified according to their average complexity. We find that thick regional input markets are conducive to start-up activity in general and complex start-ups in particular, but that some inputs are more important than others.