The R Star in the US Economy

Kristoff: It's not from China that we should expect sort of support for the western economy. So why is the US economy, as we discussed earlier, holding off so well despite this lack of momentum in China? I kind of need to give a question on what is typically labeled the R star by economist. Are we at levels where we're still surprised by the R star level in US economy? Kristoff: Is that what's driving all of John Williams' support for the US economy?