predict.cusp {cusp} | R Documentation |
Predict method for Cusp Model Fits
Description
Predicted values based on a cusp model object.
Usage
## S3 method for class 'cusp'
predict(object, newdata, se.fit = FALSE, interval =
c("none", "confidence", "prediction"), level = 0.95, type = c("response", "terms"),
terms = NULL, na.action = na.pass, pred.var = res.var/weights, weights = 1,
method = c("delay", "maxwell", "expected"), keep.linear.predictors = FALSE, ...)
Arguments
object |
Object of class " |
newdata |
An optional data frame in which to look for variables with which to predict. If omitted, the fitted values are used. |
se.fit |
See |
interval |
See |
level |
See |
type |
See |
terms |
See |
na.action |
See |
pred.var |
See |
weights |
See |
method |
Type of prediction convention to use. Can be abbreviated. ( |
keep.linear.predictors |
Logical. Should the linear predictors (alpha, beta, and y) be returned? |
... |
further arguments passed to or from other methods. |
Details
predict.cusp
produces predicted values, obtained by evaluating the regression functions from the
cusp object
in the frame newdata
using predict.lm
. This results in linear
predictors for the cusp control variables alpha
, and beta
, and, if method = "delay"
,
for the behavioral cusp variable y
. These are then used to compute predicted values: If
method = "delay"
these are the points y*
on the cusp surface defined by
V'(y*) = \alpha + \beta y* - y*^3 = 0
that are closest to y
. If method = "maxwell"
they are
the points on the cusp surface corresponding to the minimum of the associated potential function
V(y*) = \alpha y* + 0.5 y*^2 - 0.25 y*^4
.
Value
A vector of predictions. If keep.linear.predictors
the return value has a "data"
attribute
which links to newdata
augmented with the linear predictors alpha
, beta
, and, if
method = "delay"
, y
. If method = "expected"
, the expected value from the equilibrium
distribution of the stochastic process
dY_t = V'(Y_t;\alpha, \beta)dt + dW_t,
where W_t
is
a Wiener proces (aka Brownian motion) is returned. (This distribution is implemented in
dcusp
.)
Note
Currently method = "expected"
should not be trusted.
Author(s)
Raoul Grasman
References
See cusp-package
.
See Also
Examples
set.seed(123)
# example with regressors
x1 = runif(150)
x2 = runif(150)
z = Vectorize(rcusp)(1, 4*x1-2, 4*x2-1)
data <- data.frame(x1, x2, z)
fit <- cusp(y ~ z, alpha ~ x1+x2, beta ~ x1+x2, data)
newdata = data.frame(x1 = runif(10), x2 = runif(10), z = 0)
predict(fit, newdata)