This paper explores a number of statistical models for predicting the
daily stock return volatility of an aggregate of all stocks traded on
the NYSE. An application of linear and non-linear Granger causality te
sts highlights evidence of bidirectional causality, although the relat
ionship is stronger from volatility to volume than the other way aroun
d. The out-of-sample forecasting performance of various linear, GARCH,
EGARCH, GJR and neural network models of volatility are evaluated and
compared. The models are also augmented by the addition of a measure
of lagged volume to form more general ex-ante forecasting models. The
results indicate that augmenting models of volatility with measures of
lagged volume leads only to very modest improvements, if any, in fore
casting performance. (C) 1998 John Wiley & Sons, Ltd.