Ruizhi Zhu

We examine the implications of privacy-motivated targeting restrictions on consumer welfare, advertisers' customer acquisition costs, and platform revenue. In our model, competitive product firms reach consumers by placing informative ads on a monopoly advertising platform; consumers are horizontally differentiated in their product preferences and in their willingness to pay for a non-preferred product, but they don't have any intrinsic privacy preferences, nor an aversion to advertising per se.

In this context we show that both platform and consumers would be better off without any privacy restrictions if ad rates were exogenous to the privacy regime. However, in the more realistic scenario of endogenous ad rates, consumers with flexible product preferences are likely to be better off under privacy. We argue that a platform with market power selling informative ads to competitive product firms will recognize the threat to ad volume posed by cross-selling through mistargeted ads. To compensate, the platform will lower ad rates, which will then be passed on to consumers in the form of lower product prices.

We test the impact of marketing employees on brand performance metrics by inspecting how marketing employee turnover ---stratified by seniority, role and type---affects brand buzz and brand equity. Using a novel dataset that combines detailed employment records with brand metrics for 477 firms from 2012 to 2020, we find strong evidence that marketing employee turnover leads to significant declines in both brand buzz and brand equity, with the departure of a senior marketing executive estimated to reduce brand buzz and equity by approximately 3.9\% and 1.5\% of the median within-firm standard deviation, respectively. Effects are higher for employees in digital marketing roles and for employees who find another similar- or higher-seniority marketing job within 6 months (``successfully reemployed''), and are lower for those who do not secure another marketing job after their exit (``non-reemployed''). Turnover of mid-level managers and junior employees produces significant and meaningful (albeit monotonically smaller) negative impacts. Results are robust to both exhaustive two-way fixed effects and IV analysis based on turnover at peer-of-peer firms, in both cases controlling for industry-specific time trends, and compare to null effects in placebo tests. Taken together, our study provides novel quantitative estimates of the importance of marketing professionals for brands.

Virtual brands, established by firms beyond their original brands to sell their existing products on online platforms, are gaining prominence on various food-delivery platforms. This paper studies a firm's decision to create multiple brands on an online platform and the platform's decision to recommend them to consumers who make their purchase decisions after searching recommended brands on the platform. We find a multi-product firm can utilize multiple identical-menu brands with different leading products to communicate information about its product variety, enticing more consumers to search its brands on the platform. Surprisingly, such information transmission by a multi-product firm raises not only consumer surplus but also the profit of the single-product firm that does not utilize virtual brands. We find that under privacy environment where the platform does not have access to consumer-preference information, it facilitates this information transmission by consistently recommending all brands to all consumers. By contrast, under no privacy where the platform knows consumer types, it uses brands with different leading products to target different consumer segments, which essentially restricts the information-transmission channel. Interestingly, however, the profits of both the platform and the virtual-brand-offering firm increase as a result. Finally, we show banning identical-menu virtual brands can further benefit both the multi-product firm and consumers when the ban pushes the multi-product firm to create multiple virtual brands specializing in distinct products. However, when the ban leads the multi-product firm to keep only one brand with all its products, the ban can hurt consumers and all firm types.

Firms selling products to consumers realize that it takes time to learn consumers' preferences (say, by tracking their online behavior). What makes it even more challenging is that consumers' preferences may change over time, depreciating the value of acquired information. How should the firm personalize its offers and change them dynamically to learn as well as adapt to changing tastes? How should consumers behave in light of these dynamic offers? I build a continuous-time bargaining model with one-sided incomplete information where a buyer's binary type is publicly revealed through Brownian motion and the binary type changes via a Poisson process. In equilibrium, firms will start with high prices which will only be accepted by high-type consumers with positive probability and as belief drifts below a certain threshold, the firm will offer the lowest price that will be accepted by both types immediately. Changing tastes have two effects: a level effect that leaves low value consumers less likely to accept a given offer and a slope effect so that the firm screens high value consumers faster. Hence type change benefits both types of consumers at a cost to the firm. If the firm is restricted to constant prices and can use the acquired information to select consumers, it is better off than under dynamic prices. The continuation bargaining process gets resolved slower under fixed prices than under flexible prices, which makes consumers more willing to accept a given offer quicker.

This paper investigates the effect of a tailored news report and its targeted release by an ideologically biased firm. Targeted media strategies include selective information disclosure and audience targeting, with audience targeting being a novel method of distorting information to voters. When the media firm cannot commit to either strategy, targeted media provides are less biased than traditional media. With full commitment in both strategies, however, targeted media do not necessarily generate more bias because selective audience targeting may be more effective in channeling the bias.