(D) (), (I), (G) (NX), D = C + I + G + NX. D = C + I.
() , - . : 1) ( ); 2) ( , , , , .).
( average propensity to consume) , :
= / = / ( 20.1)
( marginal propensity to consume) , :
= / =D / D (20.2)
() , . (), (S), ..
= + S (20.3)
(S) , . , .
(S averege propensity to save) :
S = / = S / (20.4)
(S marginal propensity to save) , , :
S = / = DS/ D (20.5)
, D + DS = D + MPS = 1.
, = 1 MPS MPS = 1 .
, .. .
. , .. AD = C + I. : , .
. -, . . -, . , , . , , .. .
|
|
, , I = f(r), . (r), (I). S = f(r), . . , S = f(), , I = f(r).
, ( ).
r
S
r1
E
r0
I
r2
S = I
I, S
.20.11.
( )
, . . . .
.20.12. . QE , , , , D = AS.
, . , , , , . . , .
. , , . . , .
I, S S
B
E
I I
QA QE QB
.20.12.
450
I, C
B + I
E
QA QE QB
. 20.13.
. 20.13. 450 , . , .
. C+I .
, , . , D = AS.
. , , D < AS.
. , , . , , , .
|
|
( . multiplicator ) , , , .
, :
()= / = D / D I (20.6)
= 1 / 1 = 1 / MPS, (20.7)
, MPS . .
(. 20.14). , = 60 , = 40, S = 20. I = 20. 10 .
. 20.14. 20 . . . 1. = 3, D/D I = 30/10 = 3 1/ MPS = 3.
, , 20 .
I,S S
E1
30 I1
E 10
20 I
0
30 60 90 100
. 20.14.
( )
, .
I,S S1
1 S
I
0 QE1 QE
. 20.15.
( )
.20.15. S, (QE1). , . , . , .
, . , .
, , , . :
It = a(yt yt-1), (20.8)
It , a , yt , yt-1 .