Sorry if it sounds convoluted, but just trying to convey the actual rationale for the GDP equation (which is ignored or forgotten in most media reports). You understand GDP (It's not adding up all the things that were made, it's measuring the value an economy produced.). Imports clearly don't count as value an economy produced, and should not be in GDP.
But if I import something, that increases GDP (spending is positive to GDP). That starts to mess up the GDP numbers, because that spending is not value an economy produced. You have two choices, try to break down every purchase into domestic or import (impossibly complicated), or just leave it all in, and subtract out total imports at the end to nullify all the import spending (or foreign investment).
If imports went up in Q2, that means spending on imports went up. Those two cancel out for no net change to GDP.
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My best shot at not being convoluted:
Why do we subtract imports in the GDP equation? It is not because imports reduce domestic production, it is because those imports inadvertently get added in the GDP equation as spending/investment. So to remove the effect of imports entirely, we need to subtract total imports.
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Last edit. :)
From the fed:
GDP measures domestic production of final goods and services. The expenditure approach calculates GDP using total spending on domestic goods; but the equation, as stated, can lead to a misunderstanding of how imports affect GDP. More specifically, the expenditure equation seems to imply that imports reduce economic output. For example, in nearly every quarter since 1976, net exports (X – M) have been negative (see the graph and Table 1), which seems to imply that trade reduces domestic output and growth. This can influence people's perspective on trade. This essay explains that the imports variable (M) corrects for the value of imports that have already been counted as personal consumption (C), gross private investment (I), or government purchases (G). And remember, the purchase of domestic goods and services should increase GDP, but the purchase of imported goods and services should have no direct impact on GDP.
https://research.stlouisfed.org/publications/page1-econ/2018...
