Abstract:
In this study, a Fractional Frequency Flexible Fourier Form DF-type unit root test is proposed. The small sample properties of the proposed test are found to be better than that of the integer frequency counterpart. •Fractional Frequency Flexible Fourier Form-DF-type of unit root test is proposed.•The small sample properties of FFFFF-DF-type test are better than EL test.•FFFFF-DF-type test improves the empirical testing performance.•FFFFF-DF-type test prevents type two errors and over-filtration problems.