White noise testing using wavelets

Testing whether a time series is consistent with white noise is an important task within time series analysis and for model fitting and criticism via residual diagnostics. We introduce three fast and efficient white noise tests that assess spectral constancy via the wavelet coefficients of a periodogram. The Haar wavelet white noise test derives the exact distribution of the Haar wavelet coefficients of the asymptotic periodogram under mild conditions. The single‐coefficient white noise test uses a single Haar wavelet coefficient obtaining a test statistic as a linear combination of odd‐indexed autocorrelations. The general wavelet white noise test uses compactly supported Daubechies wavelets, shows that its coefficients are asymptotically normal and derives its theoretical power for an arbitrary spectrum. All our tests are available in the freely available hwwntest package for the R system. We present a comprehensive simulation study that shows the good performance of our new tests against alternatives commonly found in available software and show an example applied to a wind power time series.