The limitations of economic models

From the host of EconTalk (WSJ):

The models have been run and the numbers crunched: Bernie Sanders’s presidential platform, if enacted, would create 26 million jobs and 5.3% growth. An economist has done the calculating, and there’s no use arguing with mathematics. CNN’s headline reads: “Under Sanders, income and jobs would soar, economist says.”

When I run that line by Russ Roberts, he replies with a joke: “How do you know macroeconomists have a sense of humor? They use decimal points.”