Judging by the presidential candidates’ early speeches, the central economic issue of the 2016 campaign is already clear: the dismal performance of workers’ wages.

Families “haven’t gotten a raise in 15 years,” former Florida Gov. Jeb Bush, a Republican, said recently. In her speech last week on the economy, Democrat Hillary Clinton mentioned wages eight times. Other candidates have lavished similar attention on the plight of middle-class workers.

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