This dissertation consists of three essays in the areas of Industrial Organization and Applied Microeconomics. The first essay studies high-tech firms' product portfolio choices under competition. I develop a model of dynamic portfolio adjustments in the context of the Chinese smartphone market, using the product life cycle as an empirically tractable heuristic to capture firms' dynamic incentives in new product introductions. I first show that product life cycles endogenously arise in markets with rapid technological innovations, are heterogeneous across products, and are affected by the level of market competition. I then estimate smartphone demand and manufacturers' variable, maintenance and sunk introduction costs on a detailed monthly market-level dataset of Chinese smartphones between 2009 and 2014. Finally, I use a 2012 large-scale pro-competitive policy introduced by the Chinese government as an experiment to decompose the handset manufacturers' incentives to introduce new products and show that the increased competition reduces the average product's short-run profits by 5% but its lifetime profits by 41% by shrinking its product life cycle. These dynamic incentives have large implications for both consumer welfare gains from product variety and the speed of technology adoption in this market. In the second essay, my co-authors and I explore the sensitivity of the U.S. government's ongoing incentive auction to multi-license ownership by broadcasters. We document significant broadcast TV license purchases by private equity firms prior to the auction and perform a prospective analysis of the effect of ownership concentration on auction outcomes. We find that multi-license holders are able to raise spectrum acquisition costs by 22% by strategically withholding some of their licenses to increase the price for their remaining licenses. We analyze a potential rule change that reduces the distortion in payouts to license holders by up to 80%, but find that lower participation could greatly increase payouts and exacerbate strategic effects. The third essay studies whether liberalizations of gun permits in the U.S. deterred violent crimes. Setting off an ongoing controversy, Lott and Mustard (1997) famously contended that so-called shall-issue laws (SILs) deterred violent crime. In this controversy the weapon of choice has been the differences-in-differences (DD) estimator applied to state and county panel data spanning various intervals of time. By treating violent crime as a career choice, this essay brings to bear a more general method, a cohort panel data model (CPDM) that incorporates the fundamental dynamic insights regarding entering and exiting a career. Our model distinguishes among three key parameters that jointly determine the effect of SILs on crime, (i) a direct effect on entry decisions, (ii) a surprise effect on exit decisions by individuals who entered criminal careers prior to the passage of SILs, and (iii) a selection effect on exit decisions by those who entered in the presence of SILs. We find significant and time-invariant results that reject the deterrence hypothesis as well as the DD model specification. Our results suggest that passages of SILs contribute to about one third of total violent crimes in 2011, particularly through higher turnover of violent criminals.