Testing for a Fractional Unit Root in Time Series Regression Chingnun Lee, Tzu-Hsiang Liao2 and Fu-Shuen Shie Inst. of Economics, National Sun Yat-sen Univ Kaohsiung, Taiwan Dept. of Finance, National Central Univ, Chung-Li, Taiwan
1. Recall the assumption for the CMLRM: (Homoskedasticity) 2. Counterexamples 1、rich family and poor family expenditures; 2、large company and small company sales. There exists heteroskedasticity in lots of econometric problems
