  This paper presents the identification of heterogeneous elasticities in the
Cobb-Douglas production function. The identification is constructive with
closed-form formulas for the elasticity with respect to each input for each
firm. We propose that the flexible input cost ratio plays the role of a control
function under "non-collinear heterogeneity" between elasticities with respect
to two flexible inputs. The ex ante flexible input cost share can be used to
identify the elasticities with respect to flexible inputs for each firm. The
elasticities with respect to labor and capital can be subsequently identified
for each firm under the timing assumption admitting the functional
independence.
