Ljung-Box test to determine white noise of time-series (not residual)

Question

I know we use Ljung-Box test to determine if the residuals are white noise or not. Can we use same test to determine if the time-series in itself is white - noise? This is to by-pass acf-pacf plotting, as I need to forecast some hundred's of series.

Answer 1

Yes, absolutely. In fact, this is the case for which the Box-Pierce test, and its later refinement, the Ljung-Box test were designed.

The application of the test to residuals - which, from a subject matter point of view, is often the more interesting hypothesis to test as there are not many time series which might conceivably be white noise - in turn is fraught with certain difficulties, which are described for example here.