“…As Ramachandran and Beaumont (2001) and Smallwood and Norrbin (2008) estimated one factor GG process, without checking the sample spectral densities of interest rates, so there are opportunities to improve upon these results. We can extend their work by estimating the GG process, using the techniques developed in Chan and Tsai (2012), Hidalgo and Soulier (2004), Holan (2012, 2016), and Tsai, Rachinger, and Lin (2015). In addition, the previous literature considers tests of unit roots against long memory processes, but we may also consider that the differenced series may have long memory properties such as a stationary multifactor GG 1 process.…”