# pbltest: Baltagi and Li Serial Dependence Test For Random Effects... In plm: Linear Models for Panel Data

## Description

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BALT:LI:95;textualplm's Lagrange multiplier test for AR(1) or MA(1) idiosyncratic errors in panel models with random effects.

## Usage

 ```1 2 3 4 5 6 7``` ```pbltest(x, ...) ## S3 method for class 'formula' pbltest(x, data, alternative = c("twosided", "onesided"), index = NULL, ...) ## S3 method for class 'plm' pbltest(x, alternative = c("twosided", "onesided"), ...) ```

## Arguments

 `x` a model formula or an estimated random–effects model of class `plm` , `...` further arguments. `data` for the formula interface only: a `data.frame`, `alternative` one of `"twosided"`, `"onesided"`. Selects either H_A: ρ \neq 0 or H_A: ρ = 0 (i.e., the Normal or the Chi-squared version of the test), `index` the index of the `data.frame`,

## Details

This is a Lagrange multiplier test for the null of no serial correlation, against the alternative of either an AR(1) or a MA(1) process, in the idiosyncratic component of the error term in a random effects panel model (as the analytical expression of the test turns out to be the same under both alternatives, \insertCite@see @BALT:LI:95 and @BALT:LI:97plm. The `alternative` argument, defaulting to `twosided`, allows testing for positive serial correlation only, if set to `onesided`.

## Value

An object of class `"htest"`.

Giovanni Millo

## References

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BALT:LI:95plm

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BALT:LI:97plm

`pdwtest()`, `bgtest`, `pbsytest()`, `pwartest()` and `pwfdtest()` for other serial correlation tests for panel models.
 ```1 2 3 4 5 6 7 8 9``` ```data("Grunfeld", package = "plm") # formula interface pbltest(inv ~ value + capital, data = Grunfeld) # plm interface re_mod <- plm(inv ~ value + capital, data = Grunfeld, model = "random") pbltest(re_mod) pbltest(re_mod, alternative = "onesided") ```