Canada and the United States Had Approximately the Same Aggregate

Essay

Canada and the United States had approximately the same aggregate unemployment rates
from the 1920s to 1981.In 1982, a two percentage point gap appears, which has roughly
persisted until today, with the Canadian unemployment rate in the third quarter of 2002
being 7.6 percent while the American rate stood at 5.9 percent in the same period.
Several authors have investigated this phenomenon.One study, published in 1990,
contained the following statement: "It is a clichė that, as compared to analysis in the
physical sciences, economic analysis is hampered by the lack of controlled experiments.
In this regard, study of the Canadian economy can be much facilitated by comparison
with the behaviour of the US …" Discuss what the authors may have had in mind.List
some potential threats to internal and external validity when comparing aggregate
unemployment rate behavior between countries.