Why is matching on more than one variable be difficult? Why would matching be useful in your example?
What will be an ideal response?
When you match on multiple variables, it might be easy to come up with close matches on one of them, but with each succeeding variable, the matches are likely to be weaker. The matching that you end up with will also differ if you match on variables in different orders.
Matching can be useful because it would reduce the differences across groups that are due to individual differences.
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The Constitution allows states to
A. raise an army in peacetime. B. make commercial agreements with other states without the consent of Congress. C. govern intrastate commerce. D. print money. E. govern interstate commerce.
What powers belong to both the federal and state governments?
a. Concurrent b. Reserved c. Police d. Enumerated