Heredity or Environment: Why is Automobile Longevity Increasing?
研究了1950-1991年间汽车寿命大幅增长的原因，区分了汽车自身耐久性提升和外部环境改善（如事故率下降、维修零件降价）的影响，发现增长完全由外部环境驱动。
Over the past 25 years the longevity of automobiles has increased dramatically. We disentangle the rise in longevity into an embodied or inherent‐durability effect and a disembodied effect (driven by the external environment, such as reduced accident rates or reductions in the prices of auto repair parts) and estimate these effects by year from 1950 through 1991. We find that the entire rise in auto longevity is due to some force disembodied from the cars themselves and offer some speculation about the nature of this external environment.