Radiospectrum is a vital input in the provision of mobile services. Additional spectrum enhances the coverage and capacity of mobile networks, enabling them to meet the ever-growing demand for mobile data. Yet attaching an appropriate value to spectrum is a perennial problem for regulators and operators – regulators must decide how to allocate spectrum and set reserve prices for spectrum auctions, while operators must decide what the spectrum is worth to them (and so whether to bid at auction). This Insight explores the role of econometrics in spectrum valuation, and discusses some key findings from Plum’s econometric modelling work.