where G1 and G2 are the long run (steady state) government expenditure shares, as in (a two sector
approximation of) eq. (24).
Aggregate human capital in efficiency units (skilled labor supply) is:
H(t) = βN(t) f θθ2 ds. t-D 2 | |
Dividing by popula ' , β β h(t) = -nh(t) + 2 e |
tion, h(t) ≡ H(t)/N(t), and differentiating with respect to time: -nTr(1-θo(t-Tr)) (1 + θo(t - Tr) - 2γ)-2e-nD(1-θo(t-D)) (1 + θ0(t - D) - 2γ), |
implying steady st We know from |
[en(-Tr) - en(-D)] (1-θ0)(1+θ0-2γ) ate level h = β1-----------------------------. 2n . the definitions in the text that the arrival rate of innovation in industry ω ∈ [0, 1]at 1 (t) = μI1(t) - n and (A 2.10a) 2( ) = μI2(t) - n. (A 2.10b) x2(t) |
Hence the skilled l |
abour market equilibrium (where 2 for high tech and 1 for low tech - using equal |
weight for each) is: |
h(t) = 2I1(t)x1(t) + 1 I2(t)x2(t). (A 2.11) |
Notice that, from t |
he main text, the free entry condition into R&D is |
v(t, ω) = bwH x(t, ω),
and the Euler equation is:
Rewriting the main text eq. (12) as
v1 (t)
v2(t)
(A 2.12)
(A 2.13)
(A 2.14a)
(A 2.14b)
c. (t)
c(t) =r(t)- ρ
λλ-1 (c(t)+ β1(t)) j
= ---------------∙---------, and
ρ + I1(t) - v1-(t) - n
= λλ-1 (c(t)+ β2(t))
ρ + I2(t) - vf(t) - n
Eq.s (A 2.4)- (A 2.14b) incorporates a system of delayed differential equations in the following
unknown functions of time: θ0(t), c(t), WS (t), wH (t), h(t), m(t), β1 (t), β2(t), x1(t), x2(t), I1(t),
I2(t), v1 (t), v2(t). They cannot be solved analytically, but we can discretize them and simulate them
numerically. This has been done in the text. The existence of leads and lags implies a large number of
eigenvalues. Our discrete time simulations have been carried out using Matlab and Dynare softwares37.
37The .mod files used for the simulation and the .m files used to find the steady state are available upon request to
the authors.
24