An earth object.
This is the only required argument.
newdata
Make predictions using newdata, which
can be a data frame, a matrix, or a vector with length equal to a multiple of the number of columns
of the original input matrix x.
Note that this is more flexible than the predict methods for most R models.
NAs are allowed (and the predicted value will be NA unless the NAs are in variables
that are unused in the earth model).
Default is NULL, meaning return values predicted from the training set.
type
Type of prediction.
One of "link" (default), "response", "earth", "class", or "terms".
See the Note below.
interval
Return prediction or confidence levels.
Default is "none".
Use interval="pint" to get prediction intervals on new data.
Requires that the earth model was built with varmod.method.
This argument gets passed on as the type argument to predict.varmod.
See its help page for details.
level
Confidence level for the interval argument.
Default is .95, meaning construct 95% confidence bands
(estimate the 2.5% and 97.5% levels).
thresh
Threshold, a value between 0 and 1 when predicting a probability.
Only applies when type="class".
Default is .5.
See the Note below.
trace
Default FALSE. Set to TRUE to see which data, subset, etc. predict.earth is using.
...
Unused, but provided for generic/method consistency.
Value
The predicted values (a matrix for multiple response models).
If type="terms", a matrix with each column showing the contribution of a predictor.
If interval="pint" or "cint", a matrix with three columns: fit: the predicted values lwr: the lower confidence or prediction limit upr: the upper confidence or prediction limit
If interval="se", the standard errors.
Note
Predicting with standard earth models
Use the default type="link", or possibly type="class".
Actually, the "link", "response", and "earth"
choices all return the same value unless the glm argument
was used in the original call to earth.
Predicting with earth-GLM models
This section applies to earth models with a GLM component, i.e.,
when the glm argument was used
in the original call to earth.
The "link" and "response" options:
see predict.glm for a description of these.
In brief: for logistic models
use type="link" to get log-odds and
type="response" to get probabilities.
Use option "earth" to get the linear fit (this gives the prediction you would get
if your original call to earth had no glm argument).
Predicting with "class"
Use option "class" to get the predicted class.
With option "class", this function first makes predictions with
type="response" and then assigns the predicted values to classes as follows:
(i) When the response is a logical, predict TRUE if
the predicted probability is greater than thresh.
(ii) When the response is a numeric, predict TRUE if
the predicted value is greater than thresh.
Actually, this is identical to the above case,
although thresh here may legitimately be a value
outside the 0...1 range.
(iii) When the response is a two level factor,
predict the second level if its probability is more than thresh.
In other words, with the default thresh=.5 predict the most probable level.
(iv) When the response is a three or more level factor,
predict the most probable level (and thresh is ignored).
Predicting with "terms"
The "terms" option returns a "link" response suitable for termplot.
Only the additive terms and the first response (for multi-response models) are returned.
Also, "terms" always returns the earth terms, and ignores the GLM component
of the model, if any.
See Also
earth,
predict
Examples
data(trees)
earth.mod <- earth(Volume ~ ., data = trees)
predict(earth.mod) # same as earth.mod$fitted.values
predict(earth.mod, c(10,80)) # yields 16.8