Backfill Bias与Surviorship Bias

同问啊！

xiaopouyou 发表于 2010-5-12 14:24
简单地说，survivorship bias 是由于剔除了坏记录（运作不好的基金消失了），backfill bias是由于增加了好记 ...

+1.

The short lifetimes of many hedge funds means that there are many new entrants and many departures each year, which raises the problem of survivorship bias. If we examine only funds that have survived to the present, we will overestimate past returns because many of the worst-performing funds have not survived, and the observed association between fund youth and fund performance suggests that this bias may be substantial.

When a fund is added to a database for the first time, all or part of its historical data is recorded ex-post in the database. It is likely that funds only publish their results when they are favorable, so that the average performances displayed by the funds during their incubation period are inflated. This is known as "instant history bias" or "backfill bias".

学习了！