Methods and Results

We define the Total Success Index (TSI) as the area under the curve tracing a bureaucrat's rank over their career, from passing gwageo through successive appearances in the Annals. A long career with promotions into higher positions yields a large TSI.

The TSI distribution is highly skewed: while over 14,000 individuals passed the civil service examination, around 27% never appeared in the Annals at all. Fewer than 20% were mentioned ten times or more. The most prominent figures — such as Song Siyeol (3,809 mentions) and Han Myeonghoe (3,519 mentions) — all served as prime minister.

One's ranking at gwageo showed almost no correlation with eventual career success (Pearson r = 0.089). Passing the exam was necessary, but how well you scored barely mattered for your long-term trajectory.

Age at exam passage did matter: bureaucrats who passed in their early-to-mid twenties achieved the highest career success on average. Those who passed younger (under 20) or much older fared worse — a pattern also observed in modern studies of early career timing.

Bureaucrats from Seoul consistently achieved higher TSI than those from other regions, with the gap persisting throughout the dynasty's entire history.

Family background was a strong predictor: bureaucrats with more male ancestors who had also passed gwageo achieved systematically higher career success. Those with four gwageo-passing ancestors far outperformed those with none, demonstrating that Joseon's nominally meritocratic system operated within deeply entrenched patterns of elite reproduction.

The Gini coefficient measuring inequality in TSI among bureaucrats remained remarkably stable at approximately 0.52 for four centuries — from the dynasty's founding in 1392 through the 18th century. This stability suggests a consistent, self-regulating behavioral pattern in how the system distributed career outcomes.

In the mid-19th century, the Gini coefficient began rising rapidly to 0.78, signaling a dramatic breakdown in the system's equilibrium. This coincided with the emergence of four oligarch families (Andong Gims, Pungyang Jos, Yeoheung Mins, and Bannam Baks) who achieved a 2.02-fold increase in their share of gwageo passers and disproportionately occupied high offices.

These families not only dominated appointments but also began passing the examination itself with unusually high rankings, suggesting preferential treatment in what was designed to be a merit-based system. The dynasty collapsed within a generation of this destabilization, ending in 1910.