Economic growth and economic development 699
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (111.47 KB, 1 trang )
Introduction to Modern Economic Growth
If
σ > 1/δ,
then starting with NH (0) /NL (0) > (NH /NL )∗ , the economy tends to NH (t) /NL (t) →
∞ as t → ∞, and starting with NH (0) /NL (0) < (NH /NL )∗ , it tends to NH (t) /NL (t)
0 as t .
Ô
Proof. See Exercise 15.12.
Of greater interest for our focus are the results on the direction of technological
change. Our first result on weak equilibrium bias immediately generalizes from the
previous section:
Proposition 15.8. Consider the directed technological change model with knowledge spillovers and state dependence in the innovation possibilities frontier. Then
there is always weak equilibrium (relative) bias in the sense that an increase in H/L
always induces relatively H-biased technological change.
Ô
Proof. See Exercise 15.13.
While the results regarding weak bias have not changed, inspection of (15.38)
shows that it is now easier to obtain strong equilibrium (relative) bias.
Proposition 15.9. Consider the directed technological change model with knowledge spillovers and state dependence in the innovation possibilities frontier. Then
if
σ > 2 − δ,
there is strong equilibrium (relative) bias in the sense that an increase in H/L raises
the relative marginal product and the relative wage of the H factor compared to the
L factor.
Intuitively, the additional increasing returns to scale coming from state dependence makes strong bias easier to obtain, because the induced technology effect is
stronger. When a particular factor, say H, becomes more abundant, this encourages
an increase in NH relative to NL (in the case where σ > 1). However, from state
dependence, this makes further increases in NH more profitable, thus has a larger
685
