When is a system of currency exchange most likely to be used? A.
when one country trades goods with other countries
B.
when one country signs treaties with other countries
C.
when one country regulates trade between other countries
D.
when one country regulates banks in other countries

Using mr smith and his id, identify two potential internal validity threats that might affect the a—b design. tell me how that threat might impact conclusions in the a—b design. note #1: you cannot use maturation (since i already did that one for note #2: there are some mr smith id threats that won’t have much impact in a single case design.