GBefore averaging the
values in each voxel, one option is to remove any ÒuninterestingÓ time lags
and average only those time lag points that matter
åIn this example,
ÒuninterestingÓ refers to time lags whose percent signal change value is close to
zero
åIf we included these
uninteresting time lags in our mean calculation, they would pull the mean closer
to zero, making it more difficult to pick up any statistically significant
results in the ANOVA
GIn this example, the
IRF is fairly small from time lags 0-3, but begins to spike up at time lag 4. It peaks at time lag 7, declines at 9,
drops sharply by 10, and decreases steadily
from there.
åGiven this
information, one option
is to compute the mean
percent
signal change for time lags 4-9
only