There is a growing literature (e.g. Bloom, 2009) studying negative macroeconomic impacts of heightened uncertainty. One channel through which uncertainty can discourage economic activity, and investment in particular, is via real option effect, where if firms face irreversibility or fixed cost in investment, higher uncertainty will encourage them to postpone investment, or exercise their "option to wait".
My question is: which of the two forms of nonconvex adjustment costs (fixed cost vs. irreversibility) is more important for this mechanism, and how do they differ in their effects? Is there any good reference explaining the issue, preferably in discrete-time setting? (I'm aware there's large literature on real options in continuous time, but so far I'm more familiar with discrete-time macroeconomic models).