# checkresiduals

##### Check that residuals from a time series model look like white noise

If `plot=TRUE`

, produces a time plot of the residuals, the
corresponding ACF, and a histogram. If the degrees of freedom for the model
can be determined and `test`

is not `FALSE`

, the output from
either a Ljung-Box test or Breusch-Godfrey test is printed.

##### Usage

`checkresiduals(object, lag, df = NULL, test, plot = TRUE, ...)`

##### Arguments

- object
Either a time series model, a forecast object, or a time series (assumed to be residuals).

- lag
Number of lags to use in the Ljung-Box or Breusch-Godfrey test. If missing, it is set to

`min(10,n/5)`

for non-seasonal data, and`min(2m, n/5)`

for seasonal data, where`n`

is the length of the series, and`m`

is the seasonal period of the data. It is further constrained to be at least`df+3`

where`df`

is the degrees of freedom of the model. This ensures there are at least 3 degrees of freedom used in the chi-squared test.- df
Number of degrees of freedom for fitted model, required for the Ljung-Box or Breusch-Godfrey test. Ignored if the degrees of freedom can be extracted from

`object`

.- test
Test to use for serial correlation. By default, if

`object`

is of class`lm`

, then`test="BG"`

. Otherwise,`test="LB"`

. Setting`test=FALSE`

will prevent the test results being printed.- plot
Logical. If

`TRUE`

, will produce the plot.- ...
Other arguments are passed to

`ggtsdisplay`

.

##### Value

None

##### See Also

##### Examples

```
# NOT RUN {
fit <- ets(WWWusage)
checkresiduals(fit)
# }
```

*Documentation reproduced from package forecast, version 8.5, License: GPL-3*