```
library(plyr)
#Read in the ANT data (see ?ANT).
data(ANT)
head(ANT)
ezPrecis(ANT)
#Compute some useful statistics per cell.
cell_stats = ddply(
.data = ANT
, .variables = .( subnum , group , cue , flank )
, .fun = function(x){
#Compute error rate as percent.
error_rate = mean(x$error)*100
#Compute mean RT (only accurate trials).
mean_rt = mean(x$rt[x$error==0])
#Compute SD RT (only accurate trials).
sd_rt = sd(x$rt[x$error==0])
to_return = data.frame(
error_rate = error_rate
, mean_rt = mean_rt
, sd_rt = sd_rt
)
return(to_return)
}
)
#Compute the grand mean RT per Ss.
gmrt = ddply(
.data = cell_stats
, .variables = .( subnum , group )
, .fun = function(x){
to_return = data.frame(
mrt = mean(x$mean_rt)
)
return(to_return)
}
)
#Run a purely between-Ss permutation test on the mean_rt data.
mean_rt_perm = ezPerm(
data = gmrt
, dv = mrt
, wid = subnum
, between = group
, perms = 1e1 #1e3 or higher is best for publication
)
#Show the Permutation test.
print(mean_rt_perm)
```

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