Remodelling the Working–Kaldor curve: the roles of scarcity, time to maturity and time to harvest
研究稀缺性、到期时间和收获时间如何共同影响商品库存持有者的便利收益，发现交互模型优于传统加法模型，且现货价格与库存组合是衡量稀缺性的最佳指标。
To explain convenience yield accruing to commodity inventory holders, time to maturity (TTM) and TIME to harvest should interact with current scarcity. Using weekly data for corn, wheat and soyabeans (1986–2009), the interaction (multiplicative) model performs better than traditional versions that, at best, incorporate TTM additively and ignore harvests. Among the competing proxies for scarcity, the combination of spot price and inventory beats either spot price or inventory separately, but the pure spot-price version is a close second. Our model still exhibits a clear ‘Working curve’ pattern, with slopes changing with TTM and pre- versus post-harvest periods.