We consider the problem of optimally acquiring and retiring assets that are undergoing technological change over an unbounded horizon. The allowance for technological change prevents one from adopting the classic repeated-plant assumption that future replacements will be identical in costs to current asset contenders, thus confronting one with a non-stationary infinite horizon problem to solve....

It is commonly assumed that an acceleration in technological improvement should result in a more rapid introduction of new technology. Under a simple technological change model of a constant factor improvement in equipment costs per period, we show that, paradoxically, the effect is to optimally delay the introduction of new technology.

BACKGROUND Changes to Canadian Standards Association (CSA) standards for playground equipment prompted the removal of hazardous equipment from 136 elementary schools in Toronto. We conducted a study to determine whether applying these new standards and replacing unsafe playground equipment with safe equipment reduced the number of school playground injuries. METHODS A total of 86 of the 136 s...