A return index that tracks the NASDAQ stock market index can be subject to: A. survivorship bias and hence downward biased returns. B. survivorship bias and hence upward biased returns. C. backfill bias and hence upward biased returns.
Survivorship bias can result when a return series is based on a stock index. It will be biased upwards if the return calculation does not include firms that have been dropped from the index due to delistings.
