R: Summary for plm objects

summary.plm {plm} | R Documentation

## Summary for plm objects

### Description

The summary method for plm objects generates some more information about estimated plm models.

### Usage

    ## S3 method for class 'plm'
    summary(object, vcov = NULL, ..., .vcov = NULL)
    ## S3 method for class 'summary.plm'
    print(x, digits = max(3, getOption("digits") - 2),
        width = getOption("width"), subset = NULL, ...)

### Arguments

`object` | an object of class `"plm"`,
`x` | an object of class `"summary.plm"`,
`subset` | a character or numeric vector indicating a subset of the table of coefficients to be printed for `"print.summary.plm"`,
`vcov` | a variance–covariance matrix furnished by the user or a function to calculate one (see Examples),
`.vcov` | deprecated, use argument `vcov`,
`digits` | number of digits for printed output,
`width` | the maximum length of the lines in the printed output,
`...` | further arguments.

### Details

The `summary` method for plm objects (`summary.plm`) creates an object of class `c("summary.plm", "plm", "panelmodel")` that extends the plm object it is run on with various information about the estimated model like (inferential) statistics, see Value. It has an associated print method (`print.summary.plm`).

### Value

An object of class `c("summary.plm", "plm", "panelmodel")`. Some of its elements are carried over from the associated plm object and described there (`plm`). The following elements are new or changed relative to the elements of a plm object:

`fstatistic` | F statistic for joint test of significance of coefficients (class "htest") (robust F statistic in case of supplied argument `vcov`, see `pwaldtest` for details),

`coefficients` | a matrix with the estimated coefficients, standard errors, t–values, and p–values, if argument `vcov` was set to non-`NULL` the standard errors (and t– and p–values) in their respective robust variant,
`vcov` | the "regular" variance–covariance matrix of the coefficients (class "matrix"),
`rvcov` | only present if argument `vcov` was set to non-`NULL`: the furnished variance–covariance matrix of the coefficients (class "matrix"),
`r.squared` | a named numeric containing the R-squared ("rsq") and the adjusted R-squared ("adjrsq") of the model,
`df` | an integer vector with 3 components, (p, n-p, p*), where p is the number of estimated (non-aliased) coefficients of the model, n-p are the residual degrees of freedom (n being number of observations), and p* is the total number of coefficients (incl. any aliased ones).

### Author(s)

Yves Croissant

### See Also

`plm` for estimation of various models; `vcovHC` for an example of a robust estimation of variance–covariance matrix; `r.squared` for the function to calculate R-squared; `print.htest` for some information about class "htest"; `fixef` to compute the fixed effects for "within" (=fixed effects) models and `within_intercept` for an "overall intercept" for such models; `pwaldtest`

### Examples

    data("Produc", package = "plm")
    zz <- plm(log(gsp) ~ log(pcap) + log(pc) + log(emp) + unemp,
              data = Produc, index = c("state","year"))
    summary(zz)

    # summary with a funished vcov, passed as matrix, as function, and
    # as function with additional argument
    data("Grunfeld", package = "plm")
    wi <- plm(inv ~ value + capital,
              data = Grunfeld, model="within", effect = "individual")
    summary(wi, vcov = vcovHC(wi))
    summary(wi, vcov = vcovHC)
    summary(wi, vcov = function(x) vcovHC(x, method = "white2"))

    # extract F statistic
    wi_summary <- summary(wi)
    Fstat <- wi_summary[["fstatistic"]]

    # extract estimates and p-values
    est <- wi_summary[["coefficients"]][ , "Estimate"]
    pval <- wi_summary[["coefficients"]][ , "Pr(>|t|)"]

    # print summary only for coefficent "value"
    print(wi_summary, subset = "value")

[Package plm version 1.6-5 Index]