with Fergal Hanks
Models of lumpy capital adjustment are too responsive to interest rates relative to empirical evidence. We argue that allowing for small convex adjustment costs in labour can help these models better match the data. Convex costs cause labour to increase slowly in response to a shock thus smoothing out the impact on the marginal product of capital. Due to both depreciation and uncertainty over future productivity, this delay in the benefits of additional capital can have a large impact on the responsiveness of capital investment.