archTest function

ARCH test for univariate time series

Perform tests to check the conditional heteroscedasticity in a time series. The Ljung-Box statistics of squared series and a rank-based Ljung-Box test are used.

archTest(rt, lag = 10)

Arguments

• rt: A scalar time series. If rt is a matrix, only the first column is used.
• lag: The number of lags of ACF used in the Ljung-Box statistics. The default is 10.

Details

The Ljung-Box statistics based on the squared series are computed first. The rank series of the squared time series is than used to test the conditional heteroscedasticity.

Returns

The Q-statistic and its p-value. Also, the rank-based Q statistic and its p-value.

Author(s)

Ruey Tsay

See Also

MarchTest

Examples

rt=rnorm(200)
archTest(rt)