Wolfram Cloud Page

DIY Macroeconomic Model Simulation (using Mathematica)

https://macrosimulation.org/how_to_use

Monetary Economics (Wynne Godley, et al) SIM model:
Using Recurrence functions

C

s

=

C

d

⇒C

G

s

=

G

d

⇒G

T

s

=

T

d

⇒T

N

s

=

N

d

⇒N

YD =

W*

N

s

-

T

s

⇒YD = WN - T

T

d

= θ W

N

s

⇒ T = θ W N

C

d

=

α

1

YD +

α

2

H

h-1

⇒ C =

α

1

YD +

α

2

H

h-1

ΔH

s

=

H

s

-

H

s-1

=

G

d

-

T

d

⇒ Δ

H

s

= G - T

ΔH

h

=

H

h

-

H

h-1

= YD -

C

d

⇒ Δ

H

h

= YD - C
Y =

C

s

+

G

s

, and Y = W

N

d

, ⇒

N

d

= Y÷W ⇒ N = Y ÷ W ⇒ W = Y ÷ N

In[]:=

Manipulate[Module[{params,sim},ClearAll[y,yd,td,

c

s

,

c

d

,

g

s

,

g

d,

h

s

,

h

d

,

Δh

s

,

Δh

h

,c1,c2];params={

g

s

->g,θ->taxRate,c1->consumeRate,c2->overspend};sim=RecurrenceTable[{y[t]==

c

s

[t]+

g

s

[t],

Δh

s

[t]==

h

s

[t]-

h

s

[t-1],

Δh

h

[t]==

h

[t]-

h

[t-1],

c

s

[t]==

c

d

[t],

g

s

[t]==

g

d

[t],

c

d

[t]==c1yd[t]+c2

h

[t-1],td[t]==θy[t-1],yd[t]==y[t]-θy[t-1],y[0]==0,

c

s

[0]==0,yd[0]==0,

h

[0]==0,

h

s

[0]==0,td[0]==0}/.params,{y,yd,td,

c

d

,

h

d

},{t,1,50}];ListLinePlot[sim//Transpose,AxesLabel->{"Time","Value"},PlotLegends->{"y","yd","td","c","h"}]],{{g,20,"gov"},1,30},{{taxRate,.2},0.1,1.0,.1},{{consumeRate,.6},0.1,1.0,.1},{{overspend,.4},0.1,1.0,.1}]

Syntax

:"d, is incomplete; more input is needed.