modelling GDP

[sya_ouniversity]

Hi everyone,
This might be a very silly question and I apologize if it is.
In my model I use GDP (and the resulting GDP/capita) as a exogenous variable to estimate the dynamics of other variables. I now use a simple structure where the GDP is a stock, and there is a flow rate (GDP growth) coming in. The flow rate is determined by a fixed growth rate variable and multiplied by the GDP. The stock formula is then INTEG (GDP growth).

Is this an okay way to model the GDP or is there a better way? I'm unsure as this results in exponential growth and this is perhaps only true to a certain extent.

Thank you!

[LAUJJL]

Just one remark: your GDP is not exogenous being modeled, but endogenous. For the rest, your model assumes an increase in GDP proportional to the GDP itself, which automatically generates exponential growth.

JJ