Granularity comes at a cost – Game Theory
Granularity in system design, while seemingly beneficial for flexibility and competition, can introduce unforeseen costs. This post brilliantly uses game theory and real-world examples, from financial markets to sports court bookings, to illustrate how finer choices can be gamed. It's a fascinating look at the subtle trade-offs product designers and system architects face, making it a compelling read for anyone interested in system dynamics and user incentives.
The Lowdown
The article challenges the common assumption that more granularity in a system is always a good thing, arguing that finer choices in strategic environments can be exploited by users, leading to unintended consequences and reduced efficiency. The author supports this thesis with two distinct, detailed examples.
- Financial Markets and Tick Sizes:
- Initially, smaller tick sizes (price increments) seem to foster competition and tighten spreads, benefiting retail investors.
- However, if tick sizes are too small relative to the overall spread, it allows traders to "jump the queue" by making minimal price improvements.
- This disincentivizes liquidity providers, who then quote wider or less aggressively, ultimately leading to less efficient markets and wider spreads.
- The optimal granularity balances competition with incentives for liquidity provision.
- Sports Court Booking System:
- A system allowing 1-hour bookings with 30-minute start time granularity enables users to book a "middle" slot, creating unbookable 30-minute gaps on either side that can be used for free.
- Further rules, like 24-hour cancellations and staggered slot releases (e.g., 5 days in advance, 30 minutes apart), enable a "rolling lock" strategy. Users can progressively book and rebook later slots, maintaining control until their desired popular slot opens, bypassing direct competition.
- This highlights how a design choice intended for user flexibility (finer time slots) can inadvertently create complex gaming opportunities, reducing the platform's profitability and intended utilization.
While granularity often enhances flexibility and competition, it is not without its costs in systems where users can act strategically. Implementing finer increments can lower the "cost of strategic repositioning," effectively creating a more complex "game" that can be exploited by savvy users, often to the detriment of the system's overall goals.