Whichever way you measure national productivity, it’s growing at a snail’s pace both in absolute terms and compared to past growth rates. (See Sidebar.) And that’s not a good thing as increases in productivity improve our standard of living. SIDEBAR: Measures of Productivity Labor productivity, the measure most often cited, captures the amount of goods and services produced (output) with the number of hours worked to produce those goods and services. Multi-factor productivity compares output to the amount of combined inputs (labor, capital, energy, materials, and purchased services) used to produce that output. Economists argue this measure better captures the impact of technology advances. Not all experts agree productivity is an issue. Bloomberg blogger and investment expert Barry Ritholtz argues that productivity is higher than we think because our current measures fail to capture innovations in the digital world that have changed how…