Using ordinary calculus techniques, we investigate the conditions under whi
ch LeChatelier effects are signable for finite changes in parameter values.
We show, for example, that the short run demand for a factor is always les
s responsive to price changes than the long run demand, provided that the f
actor of production and the fixed factor do not switch from being substitut
es to being complements (or vice versa) over the relevant range of the pric
e change. The absence of a sign change in the complementarity/substitutabil
ity relation holds under conditions that are considerably more general than
supermodularity of the production function.