# R: Model Predictions

Predict {car} | R Documentation

## Model Predictions

### Description

`Predict` is a generic function with, at present, a single method for `"lm"` objects, `Predict.lm`, which is a modification of the standard `predict.lm` method in the stats package, but with an additional `vcov.` argument for a user-specified covariance matrix for intreval estimation.

### Usage

    Predict(object, ...)

    ## S3 method for class 'lm'
    Predict(object, newdata, se.fit = FALSE,
      scale = NULL, df = Inf,
      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, vcov., ...)

### Arguments

`object` | a model object for which predictions are desired.
`newdata, se.fit, scale, df, interval, level, type, terms, na.action, pred.var, weights` | see `predict.lm`.
`vcov.` | optional, either a function to compute the coefficient covariance matrix of `object` (e.g., `hccm`) or a coefficient covariance matrix (as returned, e.g., by `hccm`).
`...` | arguments to pass down to `Predict` or `predict` methods.

### Details

If there is no appropriate method for `Predict`, then a `predict` method is invoked. If there is a specific `predict` method for the primary class of `object` but only an inherited `Predict` method, then the `predict` method is invoked. Thus an object of class `c("glm", "lm")` will invoke method `predict.glm` rather than `Predict.lm`, but an object of class `c("aov", "lm")` will invoke `Predict.lm` rather than `predict.lm`.

### Value

See `predict` and `predict.lm`.

### Author(s)

John Fox jfox@mcmaster.ca

### References

Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.

### See Also

`predict`, `predict.lm`

### Examples

    mod <- lm(interlocks ~ log(assets), data=Ornstein)
    newd <- data.frame(assets=exp(4:12))
    (p1 <- predict(mod, newd, interval="prediction"))
    p2 <- Predict(mod, newd, interval="prediction", vcov.=vcov)
    all.equal(p1, p2) # the same

    (predict(mod, newd, se=TRUE))
    (p3 <- Predict(mod, newd, se=TRUE, vcov.=hccm)) # larger SEs
    p4 <- Predict(mod, newd, se=TRUE, vcov.=hccm(mod, type="hc3"))
    all.equal(p3, p4) # the same

[Package car version 3.0-2 Index]