Dr Simmons has an international reputation as a sports economist. He has published pioneering papers on attendance demand in football using a travel cost methodology, on football transfer markets using a sample selection model and on salary determination in Italian football using a rarely published data set. He is currently working on several topics in sports economics, including a new theoretical model of sports league behaviour, economic analysis of sports broadcasting, the labour market for players in the US National Football League and further analysis of earnings in Italian football.