Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Using transaction data on the S&P 100 index options, the authors study the effect of valuation simplifications that are commonplace in previous research on the time-series properties of implied market volatility. Using an American-style algorithm that accounts for the discrete nature of the dividends on the S&P 100 index, they find that spurious negative serial correlation in implied volatility changes is induced by nonsimultaneously observing the option price and the index level. Negative serial correlation is also induced by a bid/ask price effect if a single option is used to estimate implied volatility. In addition, the authors find that these same effects induce spurious (and unreasonable) negative cross-correlations between the changes in call and put implied volatility. Copyright 1991 by American Finance Association. See http://www.jstor.org for details.