# plmtest

##### Lagrange FF Multiplier Tests for Panel Models

Test of individual and/or time effects for panel models.

- Keywords
- htest

##### Usage

`plmtest(x, ...)`# S3 method for plm
plmtest(
x,
effect = c("individual", "time", "twoways"),
type = c("honda", "bp", "ghm", "kw"),
...
)

# S3 method for formula
plmtest(
x,
data,
...,
effect = c("individual", "time", "twoways"),
type = c("honda", "bp", "ghm", "kw")
)

##### Arguments

- x
an object of class

`"plm"`

or a formula of class`"formula"`

,- …
further arguments passed to

`plmtest`

.- effect
a character string indicating which effects are tested: individual effects (

`"individual"`

), time effects (`"time"`

) or both (`"twoways"`

),- type
a character string indicating the test to be performed:

`"honda"`

(default) for HOND:85;textualplm,`"bp"`

for BREU:PAGA:80;textualplm,`"kw"`

for KING:WU:97;textualplm, or`"ghm"`

for GOUR:HOLL:MONF:82;textualplm for unbalanced panel data sets, the respective unbalanced version of the tests are computed,

- data
a

`data.frame`

,

##### Details

These Lagrange multiplier tests use only the residuals of the
pooling model. The first argument of this function may be either a
pooling model of class `plm`

or an object of class `formula`

describing the model. For inputted within (fixed effects) or random
effects models, the corresponding pooling model is calculated
internally first as the tests are based on the residuals of the
pooling model.

The `"bp"`

test for unbalanced panels was derived in
BALT:LI:90;textualplm
(1990), the `"kw"`

test for unbalanced panels in
BALT:CHAN:LI:98;textualplm.

The `"ghm"`

test and the `"kw"`

test were extended to two-way
effects in BALT:CHAN:LI:92;textualplm.

For a concise overview of all these statistics see BALT:03;textualplm, Sec. 4.2, pp. 68--76 (for balanced panels) and Sec. 9.5, pp. 200--203 (for unbalanced panels).

##### Value

An object of class `"htest"`

.

##### Note

For the King-Wu statistics (`"kw"`

), the oneway statistics
(`"individual"`

and `"time"`

) coincide with the respective
Honda statistics (`"honda"`

); twoway statistics of `"kw"`

and
`"honda"`

differ.

##### References

BALT:13plm

BALT:LI:90plm

BALT:CHAN:LI:92plm

BALT:CHAN:LI:98plm

BREU:PAGA:80plm

GOUR:HOLL:MONF:82plm

HOND:85plm

KING:WU:97plm

##### See Also

`pFtest()`

for individual and/or time effects tests based
on the within model.

##### Examples

```
# NOT RUN {
data("Grunfeld", package = "plm")
g <- plm(inv ~ value + capital, data = Grunfeld, model = "pooling")
plmtest(g)
plmtest(g, effect="time")
plmtest(inv ~ value + capital, data = Grunfeld, type = "honda")
plmtest(inv ~ value + capital, data = Grunfeld, type = "bp")
plmtest(inv ~ value + capital, data = Grunfeld, type = "bp", effect = "twoways")
plmtest(inv ~ value + capital, data = Grunfeld, type = "ghm", effect = "twoways")
plmtest(inv ~ value + capital, data = Grunfeld, type = "kw", effect = "twoways")
Grunfeld_unbal <- Grunfeld[1:(nrow(Grunfeld)-1), ] # create an unbalanced panel data set
g_unbal <- plm(inv ~ value + capital, data = Grunfeld_unbal, model = "pooling")
plmtest(g_unbal) # unbalanced version of test is indicated in output
# }
```

*Documentation reproduced from package plm, version 2.2-5, License: GPL (>= 2)*