Lag correction is for temporal 'alignment' of different data channels. You are asked for the number
of seconds of lag time (for example, if the response of one channel is delayed
relative to some other channel). The channel is 'left-shifted' (time
is advanced) by the chosen amount. On the right end of the trace,
a group of samples equal to the lag interval is set to zero.
The main goal of lag correction is usually to correctly synchronize two
channels. To determine how much lag time to use, follow these steps:
- Identify a short-duration event (a sudden change) that affects both
of the channels in question.
- With either the Overlay command or the Multi-Channel
Display command (in the VIEW
menu), place both channels on the screen.
- Mark a block that extends from the event on one channel to the same
event on the other channel.
- Use the Basic Stats
option (ANALYZE menu) to determine
the time difference (the block duration can also be read at the top of
the Results window). This value should be used as the lag correction
for the delayed channel.