  The paper reviews two prominent approaches for the measurement of
technological complexity: the method of reflection and the assessment of
technologies' combinatorial difficulty. It discusses their central underlying
assumptions and identifies potential problems related to these. A new measure
of structural complexity is introduced as an alternative. The paper also puts
forward four stylized facts of technological complexity that serve as
benchmarks in an empirical evaluation of five complexity measures (increasing
development over time, larger R&D efforts, more collaborative R&D, spatial
concentration). The evaluation utilizes European patent data for the years 1980
to 2013 and finds the new measure of structural complexity to mirror the four
stylized facts as good as or better than traditional measures.
