Quantile integration order of decarbonized energy series using a Fourier function in the deterministic trend

A method for parameter hypothesis testing in nonparametric regression with Fourier series approach

“…Therefore, the Fourier series function becomes . This type of the Fourier series function was developed and used in a nonparametric regression model [see, [9] , [10] , [11] , [12] ]. The advantage of using the Fourier series function in nonparametric regression is being able to handle data that has a recurring trend at certain intervals and has a good statistical interpretation.…”