earth
objectevimp(object, trim=TRUE, sqrt.=TRUE)
earth
object.
TRUE
(default), delete rows in the returned matrix for
variables that don't appear in any subsets.
TRUE
,
meaning take the sqrt
of the GCV and RSS importances before
normalizing to 0 to 100.
Taking the square root gives a better indication of
relative importances because the raw importances are calculated using
a sum of squares.
Use FALSE
to not take the square root.
-unused
appended if the
variable does not appear in the final model. The columns of the matrix are (not all of these are printed by print.evimp
):
col
: Column index of the variable in the x
argument to earth
.
used
: 1 if the variable is used in the final model, else 0.
Equivalently, 0 if the row name has an -unused
suffix.
nsubsets
: Variable importance using the "number of subsets" criterion.
Is the number of subsets that include the variable (see "Three Criteria" in the chapter
on evimp
in the earth
vignette
“../doc/earth-notes.pdf”).
gcv
: Variable importance using the GCV criterion (see "Three Criteria").
gcv.match
: 1, except is
0 where the rank using the gcv
criterion differs from
that using the nsubsets
criterion.
In other words, there is a 0 for values that increase as you go
down the gcv
column.
rss
: Variable importance using the RSS criterion (see "Three Criteria").
rss.match
: Like gcv.match
but for the rss
.
nsubsets
criterion.
This means that values in the nsubsets
column decrease as you go down the column
(more accurately, they are non-increasing).
The values in the gcv
and rss
columns
are also non-increasing, except where the
gcv
or rss
rank differs from the nsubsets
ranking.earth
,
plot.evimp
data(ozone1)
earth.mod <- earth(O3 ~ ., data=ozone1, degree=2)
ev <- evimp(earth.mod, trim=FALSE)
plot(ev)
print(ev)
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