How effective are economic sanctions?

Crimean peninsula
Women and a boy with a toy Kalashnikov rifle walk past an unfinished wall painting depicting a map of Crimean peninsula and a slogan reading: "Together Forever" in Moscow, on March 24, 2014. Ukraine's acting president announced today that the ex-Soviet nation's troops have been given orders to withdraw from Crimea following the peninsula's seizure and annexation by Russia.
ALEXANDER NEMENOV/AFP/Getty Images