Unit root test ppt UNIT ROOT TESTS, COINTEGRATION, ECM, VECM, AND CAUSALITY MODELS Compiled by Phung Thanh Binh1 (SG - 30/11/2013) “EFA is destroying the brains of current generation’s researchers in this country. These tests allow determining convergence or divergence of a series without finding the exact sum. , and Chu C. Instead, new tests with non-standard distributions have had to be developed. Hall, A. Terdapat 3 cara yang umum digunakan dalam melakukan pendugaan terhadap kestasioneran data, yaitu: Melihat trend data dalam grafik Menggunakan autokorelasi dan correlogram Uji akar-akar unit (unit roots test) a. provide straightforward test of the null hypothesis of trend stationarity against the alternative of a unit root. Testing for cointegration •Engle-Granger test •Estimate potential CR in levels and test residuals for unit root using ADF test •Critical values will be different than standard ADF test because these are residuals rather than a variable itself •Johansen-Juselius test •More complicated, but generalizes easily to testing for more than one Mar 1, 2006 · The unit root test is the widely used approach for stationarity checking, which includes the DF test, ADF test, PP test, KPSS test, ERS test and NP test [13]. ppt - Download as a PDF or view online for free. Essentially, the test is an augmented (Dickey–Fuller test, similar to the test performed by Stata’s dfuller command, except that the time series is We would like to show you a description here but the site won’t allow us. pptx. H1: The time series contains a unit root. Stationary Time Series. So what does a ‘Unit Root’ mean? Unit root is a characteristic of a time series that makes it non-stationary. e. Reading 5: Time Series Analysis. Unit roots fundamentally change the properties and require different tools. from publication: Analysis of International Capital Inflows and Institutional Quality in Emerging Markets | This study The work of Kwiatkowski et al. Apr 3, 2024 · The document discusses various unit root tests used to determine if a time series is stationary or non-stationary. 5 Unit Root Tests 24 14. Testing for Unit Roots - Testing for Unit Roots Consider an AR(1): yt = a + ryt-1 + et Let H0: r = 1, (assume there is a unit root) Define q = r 1 and subtract yt-1 from both sides to | PowerPoint PPT presentation | free to view the test suggested by Engle and Granger was to estimate ^ by OLS and the test for unit roots in e^ t = y t ^0x t: Note, that since the unit root tests test the null-hypothesis of a unit root, most cointegration tests test the Null of no cointegration. If zi and zj are at the same position p, then the blocks that are of higher-numbered categories in the scheme above dominate lower-numbered categories. When testing for I(1) series, there are two broad categories of tests, those that test for unit roots and those that test for stationarity. Download scientific diagram | ADF, PP, LLC and IPS unit root test results. Introducing Integration Testing For Enhanced Overview And Benefits Of Unit Testing Ppt Presentation to increase your presentation threshold. Panel unit root tests can have the usual benefits of using a panel, in so far as increasing the number of observations ; In addition Levin and Lin (1992) have shown that the panel approach substantially increases the power of the test relative to the time series ADF tests. ” The aim of this lecture is to provide you with the key concepts of time series econometrics. Aug 20, 2017 · The integral test compares a series to an improper integral, the comparison test compares two series, the ratio test examines the limit of the ratio of successive terms, and the root test examines the limit of the nth root of terms. It is useful to extend Unit root non-stationarity Cointegration Stochastic volatility and GARCH models Dickey-Fuller test It is of practical importance to determine whether a time series has a unit root. Title: Testing for Unit Roots 1 Testing for Unit Roots. In fact while in the unit root tests the only problem is determin-ing lag lengths and deterministic elements, in cointegrating models a large number of choices has to be taken7. Uji Augmented Dickey- Fuller (ADF Test) c. test) proposed by Elliott, Rothenberg, and Stock 1996). A Dickey-Fuller test can be used to establish if the time series has a unit root. " Similar presentations the pre-testing step. (1992) "Testing for a Unit Root in Time Series Using Instrumental Variable Estimation Nov 2, 2019 · The ADF test belongs to a category of tests called ‘Unit Root Test’, which is the proper method for testing the stationarity of a time series. 33 Panel Unit Root Test. (1989) "Testing for a Unit Root in the Presence of Moving Average Errors," Biometrika, 76:49−56. Very likely, some of the results will indicate the presence of unit root while others will not. 93* HCE 18. Jan 31, 2012 · Unit Root Testing: Formal Tests to Establish Stationarity of Time Series • Dickey-Fuller (DF) Test • Augmented Dickey-Fuller (ADF) Test • Phillips-Perron (PP) Unit Root Test • Dickey-Pantula Unit Root Test • GLS Transformed Dickey-Fuller Test • ERS Point Optimal Test • KPSS Unit Root Test • Ng and Perron Test Jul 27, 2022 · The document discusses various unit root tests used to determine if a time series is stationary or non-stationary. 517 views • 26 This video explains what is meant by an Augmented Dickey Fuller test as a test for a unit root in a more complicated AR(p) process. Y t - m = r ( Y t-1 -m) + e t Y t = m (1- r) + r Y t-1 + e t Apr 13, 2021 · This implies that they are not covariance stationary; hence we cannot apply the standard linear regression to test for \(\text{b}_{1}=1\). Read less Feb 19, 2015 · Structural breaks, unit root tests and long time series - Download as a PDF or view online for free. Dec 18, 2016 · Unit Root Test-An Example. , to test whether ’Yt is I(0). , non-stationary) drift comes from the presence of a unit-root. Two other unit root tests are commonly used, in addition to or instead of the Augmented Dickey-Fuller Test, namely: Phillips-Perron (PP) test; Kwiatkowski–Phillips–Schmidt–Shin (KPSS) test; While the ADF test uses a parametric autoregression to estimate the errors, the PP test uses a non-parametric approach. One way to test the existence of cointegration is the regression method –see, Engle Aug 22, 2014 · Unit Root Test 1: What is unit root? 2: How to check unit root? 3: Types of unit root test 4: Dickey fuller 5: Augmented dickey fuller 6: Phillip perron 7: Testing Unit Root on E-views > adf. Perron (1993) "The Effect of Seasonal Adjustment Filters on Tests for a Unit Root," Journal of Econometrics, 55:57−98. 4398, Lag order = 1, p-value = 0. Let us understand its application in certain scenarios. It begins by providing examples of different types of non-stationarity, such as trends, level shifts, and changing variances. Matlab code. Nonstationary Forecast. A. Uji Philips-Perron (PP Test) Ghysels, E. An alternative test which has difference stationarity as the null suggests that exact unit roots models are often rejected in favor of more general nonlinear stochastic unit root (STUR) models. The fourth set of The understanding of the common pitfalls and best practices when performing unit root tests is important for the unwary applied researchers. • Many results of traditional statistical theory do not apply to unit root process, such as law of large number and central limit theory. SCPSchmidt Phillips. A number of statistical tests for detecting the presence of a unit root in a time series. DF-GLS . 4) is non-stationary, however, we cannot use standard t-tests to test the hypothesis that ˆ= 1. Unit root tests consider the null hypothesis that a series contains a unit root against the alternative that the series is trend stationary. The most commonly used stationarity test, the KPSS test, is due to Kwiatkowski, Phillips, Schmidt and Shin (1992) (KPSS). Apr 17, Unit Root Test 1: What is unit root? 2: How to check unit root? 3: Types of Panel Unit Root Tests. Aug 22, 2014 · The document discusses various unit root tests used to determine if a time series is stationary or non-stationary. A time series with unit roots should be transformed by first-differencing it to a covariance stationary time series, which Kapitel 14 Trends und Unit-root -Tests. While these complicate analysis, standard tools can be adapted. If a series has a unit root and follows a random walk, it has implications for regression analysis and economic forecasting. 95 + 14. res Dickey-Fuller = -10. Since such tests have low power in Dec 31, 2024 · Unit Root Tests AR(1) process Yt = δ + θYt-1 + εt with white noise εt • Dickey-Fuller or DF test (Dickey & Fuller, 1979) Test of H0: θ = 1 against H1: θ < 1, i. Methodology Panel unit root test and panel cointegration test. 2 Unit root testing section 2 . , H0 states Y ~ I(1), Y is non-stationary • KPSS test (Kwiatkowski, Phillips, Schmidt & Shin, 1992) Test of H0: θ < 1 against H1: θ = 1, i. Structural Change and Unit Roots ; In all the studies on unit roots, the issue of whether a time series is of the DS or TS type was decided by analyzing the series for the entire time period during which many major events took place Unlike unit root tests, Kwiatkowski et al. Observe that as discussed in a previous post. Jul 27, 2014 · • The name unit root is due to the fact that ρ = 1. 95) • There are also size problems (false positives) because we cannot include an infinite number of augmentation lags as might be called for with MA processes Problem Number Two : Low Power The Power of a test is the probability of rejecting a false Null Hypothesis - Unit Root Tests Low Power to Distinguish Between Unit and near Unit Root Low Power to Distinguish Between Trend and Drift Y is a unit root series; Z is a near-unit root series some problems associated with traditional unit root and stationarity tests, and Section 4. When the time series is flat (i. Here are the various cases of the test equation: a. That’s the reason by which we are asking you to show all ADF statistics in the table above. Because the model (1. Homework . USA 2Universidad del Rosario. We will say such a z is at position p. If after diagnostic tests, a time series is found to be stationary but trending, we can remove the trend by simply regressing that time series on Tested for unit roots in 14 macroeconomic time series using ADF unit root tests Could not reject the null of a unit root for 13 of 14 series (unemployment was only rejection) Results created the “unit root” era in time series/macro Nelson-Plosser data is a benchmark dataset for essentially all unit root papers! 6 02 4 1860 1900 1940 1980 IP A unit root test makes the analytical process seamless and efficient. and P. Stationarity, Non Stationarity, Unit Roots and Spurious Regression. (2002), Unit Root Tests in Panel Data: Asymptotic and Finite-Sample Properties, Journal of Econometrics, 108, 1-24. Secondly, we present the common pitfalls in developing unit root tests, and lastly, we suggest the Aug 9, 2020 · Unit root tests. Due to the statistical issues that are associated with I (1) series, this is a very difficult task. Feb 23, 2018 · It is important to state at this point, that the order of integration of a series in a regression model is determined by the outcome of a unit root test (or stationarity test). 5 Unit Root Tests 23 14. Maddala G. Thank you. 95) There are also size problems (false positives) because we cannot include an infinite number of augmentation lags as might be called for with MA processes. Trends. Pesaran (2007) panel unit root test Statistic GDP 27. Feb 19, 2015 Download as PPT, PDF 2 likes 2,958 views. Colombia September 2020 Baum & Otero Unit root tests for explosive behaviour September 20201/34 It is shown that standard tests, such as the augmented Dickey-Fuller test, cannot easily distinguish between exact unit roots and stochastic unit roots. In this chapter, the technical details of unit root and stationarity tests are kept to a minimum. In this case, she wishes to analyze the monthly sales data. Unit Root Test yes yes yes Unit Root Test ADF ADF ADF Unit Root Test PP PP Unit Root Test KPSS SCP Unit Root Test DF-GLS Note ADFAugmented Dickey-Fuller Test. Maddala and Wu (1999) P-2Spi ; The P test is distributed as ?2 under the null 作者：许梦洁 (编译) (知乎 | 简书 | 码云) 连享会 最新专题 直播Source: Ashish Rajbhandari → Unit-root tests in Stata 连享会-知乎推文列表Note: 助教招聘信息请进入「课程主页」查看。 因果推断-内生性 专题… Aug 15, 2024 · Grade 8 Statistics Powerpoint Presentation for Measures of Dispersion. Created by Justin S. doesn’t have a trend) and potentially slow- turning around zero, use the following test equation: The purpose of this slide is to outline the benefits of unit testing such as early detection of bugs, preventing new bugs, maintenance, and so on. Aug 22, 2014 · The document discusses various unit root tests used to determine if a time series is stationary or non-stationary. • We will learn a formal test for the unit root • For unit root process, we need to Apr 6, 2023 · Key steps include: 1) Performing unit root tests which show M3 is I(1); 2) Selecting a lag length of 12 for the VECM based on autocorrelation tests; 3) Conducting Johansen cointegration tests which indicate one cointegrating equation exists among the variables. 30* Hadri (2000) panel unit root test • As we find evidence of cross-sectional dependence among countries, Pesaran (2007) test should give the more reliable inference. Unit Root Test If on the basis of the Dickey-Fuller test or the augmented Dickey-Fuller test, we find one or more unit roots in a time series, it may provide yet further evidence of nonstationarity. 71501 X 2 t + 0. However, a time series with a unit root is not covariance stationary. 13* PUBLIC HCE 17. " Sep 24, 2019 · Unit Root Testing Versus Stationarity Tests. , uses the unit root test to analyze time series datasets for one of her retail stores. Unit root tests The “first generation” unit root tests, such as the Dickey–Fuller, Augmented Dickey–Fuller and Phillips–Perron tests have been shown to have relatively low power to reject their null hypothesis: that the series is non-stationary (I(1)) rather than stationary (I(0)). 12 Levin and Lin approach (LL) Aug 5, 2022 · Interesting! So how do we test whether we have a stationary (or trend-stationary) time series or not? Alternatively, we can ask a different question: what causes the non-stationary drift? A stochastic (i. (1997) Averaging individual Dickey-Fuller unit root tests according to ; Eti?i0 and varti?i0 are obtained by Monte Carlo simulation and are tabulated in Im et al. Stationarity tests, on the other hand, are for the null that Yt is I(0). • Thus the terms non-stationarity, random walk, and unit root can be treated as synonymous. • Note: Unit Root Stochastic Process will be further explained in Unit Root Test of Stationarity. Stationary Forecast. The Dickey-Fuller test (DF) tests the null hypothesis H0 of whether a unit Jan 5, 2020 · Review of Unit Root Testing. 2. wfl’. 15 Unit root test, take home message It is not always easy to tell if a unit root exists because these tests have low power against near-unit-root alternatives (e. (1999), A Comparative Study of Unit Root Tests with Panel Data and a New Simple Test, Oxford Bulletin of Economics and Statistics, 61, 631-652. 1 Introduction to spurious regression Suppose that we observe the following regression results ( t statistics in parentheses): Y t = 449. Apply the DF tests on the following three data series Exchange rate CPI index M2 money supply Monthly data 10-year data at least Q: Type of RW? Tested for unit roots in 14 macroeconomic time series using ADF unit root tests Could not reject the null of a unit root for 13 of 14 series (unemployment was only rejection) Rlt tdth“it t” iti 8 Results created the “unit root” era in time series/macro Nelson-Plosser data is a benchmark dataset for essentially all unit root papers! 1 Testing for unit roots in Eviews Open ‘ukhp. In this paper, we employ the ADF test the univariate unit root tests, say ADF, PP tests. 794 X 1 t – 0. Example #1. Finally, also the interpretation of the panel cointegration test raises even more difficulties than the interpretation of panel unit root tests. Jan 5, 2023 · It describes the Dickey-Fuller test and Augmented Dickey-Fuller test, which test for a unit root in a time series. Apr 6, 2019 · Testing Strategy for Unit Roots • Three main aspects of Unit root testing • - Deterministic components (constant, time trend). Aug 22, 2014 · Unit Root Test - Download as a PDF or view online for free. The first three settings (on the left-hand side of the dialog) determine the basic form of the unit root test. Im et al. 5 Unit Root Tests. 05, so rejects the null hypothesis of unit root (rigorously speaking, the p-value is wrong here because it is based on the Dickey-Fuller distribution. The Augmented Dickey-Fuller (ADF) test is a statistical test used in econometrics and finance to determine whether a unit root is present in a time series dataset. EloriagaWebsite: justineloriaga. In particular, any sort of structural break in the ÐÏ à¡± á; þÿ ­ þÿÿÿ« € ‚ ¬ ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿR This week, in the MAT8181 Time Series course, we’ve discussed unit root tests. 12 Testing for unit roots The Dickey-Fuller unit root test Under H0, the model for yt is: Δyt = μ + ρ1Δyt-1 + … + ρk-1Δyt-(k-1) + εt (4) which is an AR(k-1) in the first difference Δyt Thus, if yt has a (single) unit root, then Δyt is a stationary Because of this property, we say that if yt is nonstationary, but Δdyt is stationary Nov 21, 2023 · The KPSS then tests if there is a unit root in rt when β is nonzero. test(co. Note ADFAugmented Dickey-Fuller Test. res, k = 1) Augmented Dickey-Fuller Test data: co. 7. Unit Root Test . Check out https://ben-lam. ders 3. 4). Aug 6, 2014 · Unit Root Test-An Example. The ADF and PP unit root tests are for the null hypothesis that a time series Yt is I(1). Apply the DF tests on the following three data series Exchange rate CPI index M2 money supply Monthly data 10-year data at least Q: Type of RW? (Graph the data series) Selection on time lag? (Use AIC and Schwarz value ). 2 estimate mu, sigma unknown. • In practice, the cointegration vector is unknown. t. Oct 28, 2018 · Since the ADF and PP test did not take into account structural breaks, I performed a two-root structural unit root test of Lee Strazicich (2003). D. The framework for testing unit roots is Jul 27, 2012 · Stationarity, Non Stationarity, Unit Roots and Spurious Regression. To go one step further, … Continue reading Unit Root Tests → tests for a unit root in a time series. 14. 01 alternative hypothesis: stationary The p-value is less than 0. Levin A. PPPhillips Perron. (1992) was motivated by the fact that unit root tests developed by Dickey and Fuller (1979), Dickey and Fuller (1981), and Said and Dickey (1984) indicated that most aggregate economic series had a unit root. Baum r 1 Jesus Otero 2 1Boston College. g. FEB13011 Financial Methods and Techniques PART 2: Time Series Regression - Culver/Papell (2006 J. ). DF-GLSDickey-Fuller GLS. UNIT ROOT TESTS: COMMENT 1 | PowerPoint PPT presentation | free to view ÐÏ à¡± á> þÿ À  þÿÿÿÈ É Ê Ë Ì Í Î Ï Ð Ñ Ò Á Augmented Dickey-Fuller Unit Root Tests How do we know when to difference time series data to make it stationary? You use the Augmented Dickey-Fuller t-statistic. For this, they consider three-component representation of the observed time series as the sum of a deterministic time trend, a random walk and a stationary residual: 2 Testing for Unit Roots We want to be able to discriminate between the two alternative models (1. 2 Result from Panel Unit Root Test at First Different If the data non-stationary at the levels I(0), next step testing unit root by using to conduct a panel unit root test with first differences. According to Wold’s theorem, if is (weakly) stationnary then where is the innovation process, and where is some deterministic series (just to get a result as general as possible). Dickey North Carolina State University (Previously presented at Purdue Econ Dept. Firstly, this technical note aims to develop an understanding about unit roots. • - ADF Augmented Dickey Fuller test - lag length • - use F-test or Schwarz Information Criteria • - In what sequence should we test? DICKEY-FULLER (DF) TEST: The simplest approach to test for a unit root begins with AR (1) model DF test actually does not consider 0 in the model, but actually model with 0 and not 0 gives different results. Dec 2, 2022 · The document discusses various unit root tests used to determine if a time series is stationary or non-stationary. Suppose Laura, the sales head of ABC Co. , Lin C. 5. • If, however, |ρ| ≤ 1, then the time series Yt is stationary in the sense we have defined it. The document emphasizes the importance of unit root testing to Unit Root Tests Standard Dickey-Fuller test appropriate for AR(1) Said and Dickey (1984) augment the basic autoregressive unit root test to accommodate general &ndash; A free PowerPoint PPT presentation (displayed as an HTML5 slide show) on PowerShow. Mar 12, 2024 · The document discusses unit root tests, which are used to determine whether a time series follows a random walk or stationary process. 4393 X 3 t + t Slideshow 4442657 by hedy View Panel unit root tests PowerPoint PPT Presentations on SlideServe. com bottom of a unit root Jordan block dominates any other zj that is stationary or in a lower position in any unit root Jordan block. test (known as the . Unfortunately the limiting distribution of for ex- • A time series is non-stationary if it contains a unit root unit root ⇒ nonstationary The reverse is not true. Unit root tests help in assessing whether a time series is stationary. We test whether the series of ‘hp’ is unit root. So it is useful to do a test of Lee Strazicich In this video, we will learn the similarity and difference between the ADF, PP and the KPSS unit root tests in EViews. The hypothesis for the test is then: H0: The time series is trend stationary. (1997). Apr 17, 2022 · ACF. Collection of 100+ Panel unit root tests slideshows. Please stop it as much as you can. and Wu S. Because if the data stationary can help to make estimations and prediction because when the data is stationary, it is Sep 16, 2014 · Chapter 5 : Unit-root Testing and Cointegration Analysis. Please leave feadback comments. In these tests, the null hypothesis is that the series has a unit root. 4. 5 Unit Root Tests 25 14. , its statistical properties, such as mean and variance, are not constant over time. 3) and (1. A unit root implies that a series is non-stationary, i. Exhibits mean reversion in that it fluctuates around a constant long run mean Has a finite variance that is time invariant. Trend : Der Erwartungswert eines Prozesses Y t nimmt mit Fortschreiten der Zeit zu (oder ab) Deterministischer Trend : ist eine Funktion f ( t ) der Zeit, die den Erwartungswert von Y beschreibt: Slideshow 3676371 by garima Unit root tests for explosive behaviour Christopher F. com - id: 4c8d0a-MmYxY Jul 28, 2019 · 3: Types of unit root test 4: Dickey fuller 5: Augmented dickey fuller 6: Phillip perron 7: Testing Unit Root on E-views The+open+economy+&+exchange+rates videoaakash15 Jul 21, 2012 · Testing for Unit Roots • Consider an AR(1): yt = a + ryt-1 + et • Let H0: r = 1, (assume there is a unit root) • Define q = r – 1 and subtract yt-1 from both sides to obtain Dyt = a + qyt-1 + et • Unfortunately, a simple t-test is inappropriate, since this is an I(1) process • A Dickey-Fuller Test uses the t-statistic, but different Nov 15, 2014 · Unit Root Test-An Example. 242 views • 8 slides Apr 13, 2021 · Rejection of the null hypothesis implies that \(\text{b}_1-1=0\) and so the time series has a unit root. This document discusses analyzing non-stationary time series data. 6 presents some recently developed so-called “efficient unit root tests” that overcome some of the deficiencies of traditional unit root tests. Consider an AR(1) yt a ryt-1 et ; Let H0 r 1, (assume there is a unit root) Define q r 1 and subtract yt-1 from both sides to obtain Dyt a qyt-1 et ; Unfortunately, a simple t-test is inappropriate, since this is an I(1) process ; A Dickey-Fuller Test uses the t-statistic, but To begin, double click on the series name to open the series window, and choose View˜Unit Root Test˜˜˜ You must specify four sets of options to carry out a unit root test. It performs the modified Dickey–Fuller . 29* PRIVATE HCE 21. 4 Unit Root Test Using t H1: Stationary AR(1) with mean 0 H0 : Random Walk H1: Stationary AR(1) with mean 0. ϕ = 0. Roger Perman Applied Econometrics Lecture 11. Uji Dickey- Fuller (DF Test) b. It describes the Dickey-Fuller test and Augmented Dickey-Fuller test, which test for a unit root in a time series. 1 时间序列平稳性和单位根检验 Stationary Time Serial and Unit Root Test 一、时间序列的平稳性 二、单整序列 三、单位根检验. LOS 5 (k) Describe the steps of the unit root test for nonstationary and explain the relation of the test to autoregressive time-series Jan 9, 2025 · Unit root test, take home message • It is not always easy to tell if a unit root exists because these tests have low power against near-unit-root alternatives (e. The quality of the video is poor, but I hope you will find it helpful. If the series is stationary at level after performing unit root test, then it is I (0), otherwise it is I ( d ) where d represents the number of times the series is Download ppt "§8. The Augmented Dickey-Fuller test extends the Dickey-Fuller test by including lagged difference terms to account for autocorrelation. The hypothesis is the reverse of KPSS test. Submit Search. • Both tests agree that the series are integrated of order 1. 1. Appl Econometrics ) Is there a unit root in the inflation Culver/Papell (1997) 31. Aug 22, an-experimental-evaluation-of-the-reliability-. This video goes through the the concept of a unit root and the various tests for non-stationarity. KPSSKwiatkowski-Phillips-Schmidt-Shin. Unit Root Test-An Example. If the H0 (unit root) cannot be rejected, then the next step is to test cointegration among the components, i. , H0 states Y ~ I(0), Y is Comments on Unit Root Tests: Unit root tests are very sensitive to the number of included lags and/or constant and trends. ACF. ppt. ”Trend Stationary” Forecast. Therefore, there is series of unit root tests and proposals under which circumstances a test is more useful than another. 5 Download ppt "Unit Root Tests. ggms gsm ukgw muggwzk dxbua rug eanm yrs tqmxdw qewng jcgug yej alqzjrg wyp brjwn