The BlackBerry production function indicated in the text is Q = 2.83L1.52 K0.82. Epple et al. (2010) estimate that the production function for U. S. housing is q = 1.38L0.144 M0.856, where L is land and M is an aggregate of all other mobile, nonland factors, which we call materials. Haskel and Sadun (2012) estimate the production function for U. K. supermarkets is Q = L0.23K0.10 M0.66, where L is labor, K is capital, and M is materials. What kind of returns to scale do these production functions exhibit?