This data is divided into 4 groups: 1. The bone ash difference between 21 Days of age and 35 Days of age. 2. The cumulative feed intake and feed conversion ratio over the duration of the trial. 3. The
Alongside instrumental-variables and fixed-effects approaches, the control function approach is the most widely used in production function estimation. Olley and Pakes (1996, Econometrica 64: 1263–129