A simultaneous equations model of performance, strategy and size is tested using fieldwork evidence on long-lived firms in Scotland. Estimation is by I3SLS, with correction for sample selection bias. The contributions of this paper are that it: (a) grounds estimation on fieldwork evidence; (b) calibrates performance and competitive strategy; (c) tests and models endogeneity; and (d) computes robust trade-off elasticities between firm size and performance. It shows how this trade-off provides the entrepreneur with two strong incentives: (i) to seek greater efficiency typically by an increase in the human capital of the ‘core’ workforce; (ii) to achieve higher levels of performance by adopting more diverse competitive strategies
