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JGCRI / gcam-core

GCAM -- The Global Change Analysis Model
http://jgcri.github.io/gcam-doc/
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non-zero alpha in regional GDP calculation #234

Open msispah opened 1 year ago

msispah commented 1 year ago

Hi, I would like to include the effects of various sectors/industries on GDP. From GCAM manual, I found that changing alpha in the calculation of regional GDP (http://jgcri.github.io/gcam-doc/economy.html) will take energy services into account and will modify GDP accordingly. I could not find the inclusion of alpha in the xml and source code files. Can anyone please help me how to take alpha into account?

Also, Is there any other way (apart from this equation) to see the effects of sectoral level changes on GDP? Thank you.

pkyle commented 1 year ago

The alpha parameter you're referring to isn't something we've used in the model since about 2008, and since it hasn't been maintained, it likely wouldn't perform as intended. It was designed for a time when the "final demands" were all indicated in energy terms, and where the weighted average prices of the final demands could be meaningfully computed. Basically, it adjusts the GDP in each region by the "price ratio" raised to this elasticity, and I believe the price ratio is computed from the energy-final-demand prices. Nowadays reading in a non-zero parameter for the parameter e_GDP_elas will probably result in a non-sensical computation (e.g., passenger travel prices would be weighted by passenger-km, cement prices would be weighted by Mt of cement produced, and so on).

msispah commented 1 year ago

Thank you so much for the reply. Can you please answer my second question too? - Is there any other way (apart from this equation) to see the effects of sectoral level changes on GDP?