The following are four methods that could be used to detrend
these data: (1) Use a constant, as in Taylor (1993); (2) Use a linear trend; (3) Use an atheoretical filter, like the Hodrick-Prescott filter; (4) Use a model, as in Holston et al.
In this article, we detrend
our time series data with the Hodrick-Prescott (HP) filter.
In order to improve the efficiency of the multivariate models, spectral pre-processing techniques based on smoothing (moving average), detrend
, multiplicative scattering correction (MSC) and standard normal variate (SNV) can be applied.
The wavelet-based method can detrend
the records with polynomial trend because of the property of vanishing moments of wavelet, can avoid the spurious result caused by trend, and is suitable for water level records.
our data, we first attempted to fit a negative exponential curve to the individual series raw data.
Three methods are considered for comparison: RIAA, LS, and a detrend
LS (termed DLS), which uses an additional detrend
function (developed in LSPR) before regular LS periodogram estimation is applied.
Aforementioned studies often add a linear time trend to an AR(2) to detrend
Thus, in order to avoid problems of spurious regression, we decided to detrend
the time series of unemployment rates before using it in the VAR estimations.
So, both polynomials of various orders and linear functions were tested in a detrend
The essence of his methodology is to detrend
the original series with an allowance for a structural break and to conduct tests for unit roots in the detrended