We propose to estimate strategic interaction effects between general practitioners (GPs) and different specialist types to evaluate the viability threat for specialists associated to the introduction of a mandatory referral scheme. That is, we show that the specialists’ loss of patientele when...

We propose a methodology for estimating the competition effects from entry when firms sell differentiated products. We first derive precise conditions under which Bresnahan and Reiss’entry threshold ratios (ETRs) can be used to test for the presence and to measure the magnitude of competition...