The Canadian government decides to run an experiment to see if fiscal policy works. It throws 100 darts at a map of Canada. One dart lands on Wawa Ontario, so it spends an extra $1 million in Wawa. Local GDP in Wawa, and local GDP in all the other 99 places where the darts land, increases by $2 million relative to the control group of the Rest of Canada. The experiment clearly shows there's a government expenditure multiplier of 2.0.
Does that mean there's a government expenditure multiplier of 2.0 in the whole of Canada?
You should be able to see the underlying fallacy of composition. "Government spending has a multiplier of 2.0 in each part of Canada, therefore government spending has a multiplier of 2.0 in the whole of Canada."