A lot of time series analysis in economics and nance is to determine whether a unit root and/or seasonal unit root is present in the data. These tests are usually based on unit root tests orginally developed by Dickey & Fuller(1981). Testing for the presence of a seasonal root has been considered by Dickey, Hasza & Fuller (1984). Li(1991) considered tests for the existence of a seasonal and a r...

This introduction to the CADFtest package is a (slightly) modified version of Lupi (2009), published in the Journal of Statistical Software. CADFtest is an R package for testing for the presence of a unit root in a time series using the Covariate Augmented Dickey-Fuller (CADF) test proposed in Hansen (1995b). The procedures presented here are user friendly, allow fully automatic model specifica...

In this paper, we consider a sieve bootstrap for the test of a unit root in models driven by general linear processes. The given model is ...rst approximated by a ...nite autoregressive integrated process of order increasing with the sample size, and then the method of bootstrap is applied for the approximated autoregression to obtain the critical values for the usual unit root tests. The resul...

Econometricians typically make use of functional central limit theorems to prove results for I(1) processes. For example, to establish the limit distributions of unit root tests such as the Phillips–Perron and Dickey–Fuller tests, the functional central limit theorem plays a crucial role. In this paper, it is pointed out that for linear processes, minimal conditions that ensure that only a cent...

In this paper, in the first step, we show that the fractional DickeyFuller test proposed by Dolado et al [10] is useless in practice. In the second step, we propose a new testing procedure for the degree of fractional integration of a time series inspired on the unit root test of Dickey-Fuller [7]. The composite null hypothesis is that of d ≥ d0 against d < d0. The test statistics is the same a...

The purpose of this study is to investigate the asymptotics of a first order auto regressive unit root process, AR(1). The goal is to determine which tests could be used to test for the presence of a unit root in a first order auto regressive process. A unit root is present when the root of the characteristic equation of this process equals unity. In order to test for the presence of a unit roo...

The prime objective of the study is to identify the long-run and short-run relationship between Indian stock price viz., BSE SENSEX (hereafter named as BSE) and gold price (GOLD) in India. The daily closing price data were collected for the period of ten years ranging from 1st April 2004 to 31st March 2014 with 2490 observations. The study employed two models: Model one us...

This paper proposes a simple direct testing procedure to distinguish a linear unit root process from a globally stationary three-regime self-exciting threshold autoregressive process. We derive the asymptotic null distribution of the Wald statistic, and show that it does not depend on unknown fixed threshold values. Monte Carlo evidence clearly indicates that the exponential average of the Wald...