While both commodities have fallen this year, the company still suffers from a lag effect of the higher prices in 2006.

After the sun sets and the temperature drops, the warm wall will then continue to transfer heat to the interior for several hours due to the time lag effect.

At the moment, however, it may be adding to productivity problems 'due to adoption barriers and lag effects as well as transition costs'.

Signals are often generated through a contrarian mean-reversion principle but can also be designed using such factors as lead/lag effects, corporate activity, short-term momentum, etc.