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Full-Text Articles in Econometrics

A Combined Approach To The Inference Of Conditional Factor Models, Yan Li, Liangjun Su, Yuewa Xu Apr 2015

A Combined Approach To The Inference Of Conditional Factor Models, Yan Li, Liangjun Su, Yuewa Xu

Research Collection School Of Economics

This article develops a new methodology for estimating and testing conditional factor models in finance. We propose a two-stage procedure that naturally unifies the two existing approaches in the finance literature-the parametric approach and the nonparametric approach. Our combined approach possesses important advantages over both methods. Using our two-stage combined estimator, we derive new test statistics for investigating key hypotheses in the context of conditional factor models. Our tests can be performed on a single asset or jointly across multiple assets. We further propose a novel test to directly check whether the parametric model used in our first stage is …


Nonparametric Predictive Regression, Ioannis Kasparis, Elena Andreou, Peter C. B. Phillips Apr 2015

Nonparametric Predictive Regression, Ioannis Kasparis, Elena Andreou, Peter C. B. Phillips

Research Collection School Of Economics

A unifying framework for inference is developed in predictive regressions where the predictor has unknown integration properties and may be stationary or nonstationary. Two easily implemented nonparametric F-tests are proposed. The limit distribution of these predictive tests is nuisance parameter free and holds for a wide range of predictors including stationary as well as non-stationary fractional and near unit root processes. Asymptotic theory and simulations show that the proposed tests are more powerful than existing parametric predictability tests when deviations from unity are large or the predictive regression is nonlinear. Empirical illustrations to monthly SP500 stock returns data are provided. …


Lag Length Selection For Unit Root Tests In The Presence Of Nonstationary Volatility, Giuseppe Cavaliere, Peter C. B. Phillips, Stephan Smeekes, A. M. Robert Taylor Apr 2015

Lag Length Selection For Unit Root Tests In The Presence Of Nonstationary Volatility, Giuseppe Cavaliere, Peter C. B. Phillips, Stephan Smeekes, A. M. Robert Taylor

Research Collection School Of Economics

A number of recent papers have focused on the problem of testing for a unit root in the case where the driving shocks may be unconditionally heteroskedastic. These papers have, however, taken the lag length in the unit root test regression to be a deterministic function of the sample size, rather than data-determined, the latter being standard empirical practice. We investigate the finite sample impact of unconditional heteroskedasticity on conventional data-dependent lag selection methods in augmented Dickey–Fuller type regressions and propose new lag selection criteria which allow for unconditional heteroskedasticity. Standard lag selection methods are shown to have a tendency …


Qml Estimation Of Dynamic Panel Data Models With Spatial Errors, Liangjun Su, Zhenlin Yang Mar 2015

Qml Estimation Of Dynamic Panel Data Models With Spatial Errors, Liangjun Su, Zhenlin Yang

Research Collection School Of Economics

We propose quasi maximum likelihood (QML) estimation of dynamic panel models with spatial errors when the cross-sectional dimension n is large and the time dimension T is fixed. We consider both the random effects and fixed effects models, and prove consistency and derive the limiting distributions of the QML estimators under different assumptions on the initial observations. We propose a residual-based bootstrap method for estimating the standard errors of the QML estimators. Monte Carlo simulation shows that both the QML estimators and the bootstrap standard errors perform well in finite samples under a correct assumption on initial observations, but may …


Enriching Surveys With Supplementary Data And Its Application To Studying Wage Regression, Denis H. Y. Leung, Ken Yamada, Biao Zhang Mar 2015

Enriching Surveys With Supplementary Data And Its Application To Studying Wage Regression, Denis H. Y. Leung, Ken Yamada, Biao Zhang

Research Collection School Of Economics

We consider the problem of supplementing survey data with additional information from a population. The framework we use is very general; examples are missing data problems, measurement error models and combining data from multiple surveys. We do not require the survey data to be a simple random sample of the population of interest. The key assumption we make is that there exists a set of common variables between the survey and the supplementary data. Thus, the supplementary data serve the dual role of providing adjustments to the survey data for model consistencies and also enriching the survey data for improved …


Enriching Surveys With Supplementary Data And Its Application To Studying Wage Regression, Denis H. Y. Leung, Ken Yamada, Biao Zhang Mar 2015

Enriching Surveys With Supplementary Data And Its Application To Studying Wage Regression, Denis H. Y. Leung, Ken Yamada, Biao Zhang

Research Collection School Of Economics

We consider the problem of supplementing survey data with additional information from a population. The framework we use is very general; examples are missing data problems, measurement error models and combining data from multiple surveys. We do not require the survey data to be a simple random sample of the population of interest. The key assumption we make is that there exists a set of common variables between the survey and the supplementary data. Thus, the supplementary data serve the dual role of providing adjustments to the survey data for model consistencies and also enriching the survey data for improved …


Asymptotic Theory For Linear Diffusions Under Alternative Sampling Scheme, Qiankun Zhou, Jun Yu Mar 2015

Asymptotic Theory For Linear Diffusions Under Alternative Sampling Scheme, Qiankun Zhou, Jun Yu

Research Collection School Of Economics

The asymptotic distributions of the maximum likelihood estimator of the persistence parameter are developed in a linear diffusion model under three sampling schemes, long-span, in-fill and double. Simulations suggest that the in-fill asymptotic distribution gives a more accurate approximation to the finite sample distribution than the other two distributions. An empirical application highlights the difference in unit root testing based on the alternative asymptotic distributions.


Lm Tests Of Spatial Dependence Based On Bootstrap Critical Values, Zhenlin Yang Mar 2015

Lm Tests Of Spatial Dependence Based On Bootstrap Critical Values, Zhenlin Yang

Research Collection School Of Economics

To test the existence of spatial dependence in an econometric model, a convenient test is the Lagrange Multiplier (LM) test. However, evidence shows that, in finite samples, the LM test referring to asymptotic critical values may suffer from the problems of size distortion and low power, which become worse with a denser spatial weight matrix. In this paper, residual-based bootstrap methods are introduced for asymptotically refined approximations to the finite sample critical values of the LM statistics. Conditions for their validity are clearly laid out and formal justifications are given in general, and in detail under several popular spatial LM …


Bias Correction For Fixed Effects Spatial Panel Data Models, Zhenlin Yang, Jihai Yu, Shew Fan Liu Mar 2015

Bias Correction For Fixed Effects Spatial Panel Data Models, Zhenlin Yang, Jihai Yu, Shew Fan Liu

Research Collection School Of Economics

This paper examines the finite sample properties of the quasi maximum likelihood (QML) estimators of the fixed effects spatial panel data (FE-SPD) models of Lee and Yu (2010). Following the general bias correction methods recently developed by Yang (2015), we derive up to third-order bias corrections for the QML estimators of the FE-SPD model, and propose a simple bootstrap method for their practical implementation. Monte Carlo results reveal that the QML estimators of the spatial parameters can be quite biased and that a second-order bias correction effectively removes the bias. The validity of the bootstrap method is established. Variance corrections …


Nonparametric Testing For Anomaly Effects In Empirical Asset Pricing Models, Sainan Jin, Liangjun Su, Yonghui Zhang Feb 2015

Nonparametric Testing For Anomaly Effects In Empirical Asset Pricing Models, Sainan Jin, Liangjun Su, Yonghui Zhang

Research Collection School Of Economics

In this paper, we propose a class of nonparametric tests for anomaly effects in empirical asset pricing models in the framework of nonparametric panel data models with interactive fixed effects. Our approach has two prominent features: one is the adoption of nonparametric functional form to capture the anomaly effects of some asset-specific characteristics and the other is the flexible treatment of both observed/constructed and unobserved common factors. By estimating the unknown factors, betas, and nonparametric function simultaneously, our setup is robust to misspecification of functional form and common factors and avoids the well-known "error-in-variable" problem associated with the commonly used …


Sieve Instrumental Variable Quantile Regression Estimation Of Functional Coefficient Models, Liangjun Su, Tadao Hoshina Feb 2015

Sieve Instrumental Variable Quantile Regression Estimation Of Functional Coefficient Models, Liangjun Su, Tadao Hoshina

Research Collection School Of Economics

In this paper, we consider sieve instrumental variable quantile regression (IVQR) estimation of functional coefficient models where the coefficients of endogenous regressors are unknown functions of some exogenous covariates. We approximate the unknown functional coefficients by some basis functions and estimate them by the IVQR technique. We establish the uniform consistency and asymptotic normality of the estimators of the functional coefficients. Based on the sieve estimates, we propose a nonparametric specification test for the constancy of the functional coefficients, study its asymptotic properties under the null hypothesis, a sequence of local alternatives and global alternatives, and propose a wild-bootstrap procedure …


Shrinkage Estimation Of Dynamic Panel Data Models With Interactive Fixed Effects, Xun Lu, Liangjun Su Feb 2015

Shrinkage Estimation Of Dynamic Panel Data Models With Interactive Fixed Effects, Xun Lu, Liangjun Su

Research Collection School Of Economics

We consider the problem of determining the number of factors and selecting the proper regressors in linear dynamic panel data models with interactive fixed effects. Based on the preliminary estimates of the slope parameters and factors a la Bai and Ng (2009) and Moon and Weidner (2014a), we propose a method for simultaneous selection of regressors and factors and estimation through the method of adaptive group Lasso (least absolute shrinkage and selection operator). We show that with probability approaching one, our method can correctly select all relevant regressors and factors and shrink the coefficients of irrelevant regressors and redundant factors …


The True Limit Distributions Of The Anderson-Hsiao Iv Estimators In Panel Autoregression, Peter C. B. Phillips, Chirok Han Feb 2015

The True Limit Distributions Of The Anderson-Hsiao Iv Estimators In Panel Autoregression, Peter C. B. Phillips, Chirok Han

Research Collection School Of Economics

This note derives the correct limit distributions of the Anderson-Hsiao (1981) levels and differences instrumental variable estimators, provides comparisons showing that the levels IV estimator has uniformly smaller variance asymptotically as the cross section (n) and time series (T) sample sizes tend to infinity, and compares these results with those of the first difference least squares (FDLS) estimator. (C) 2014 Elsevier B.V. All rights reserved.


Limit Theory For An Explosive Autoregressive Process, Xiaohu Wang, Jun Yu Jan 2015

Limit Theory For An Explosive Autoregressive Process, Xiaohu Wang, Jun Yu

Research Collection School Of Economics

Large sample properties are studied for a first-order autoregression (AR(1)) with a root greater than unity. It is shown that, contrary to the AR coefficient, the least-squares (LS) estimator of the intercept and its t-statistic are asymptotically normal without requiring the Gaussian error distribution, and hence an invariance principle applies. The coefficient based test and the t test have better power for testing the hypothesis of zero intercept in the explosive process than in the stationary process.


Nonparametric Threshold Regression: Estimation And Inference, Daniel J. Henderson, Christopher F. Parmeter, Liangjun Su Jan 2015

Nonparametric Threshold Regression: Estimation And Inference, Daniel J. Henderson, Christopher F. Parmeter, Liangjun Su

Research Collection School Of Economics

The present work describes a simple approach to estimating the location of a threshold/changepoint in a nonparametric regression. This model has connections both to the time-series and regressiondiscontinuity literatures. The estimator leverages a simple decomposition, giving it the form of asemiparametric smooth coefficient model. Optimal bandwidth selection and a suite of testing facilitiesare also presented. Several empirical examples are provided to illustrate the implementation of themethods discussed here.


Specification Testing For Transformation Models With An Application To Generalized Accelerated Failure-Time Models, Arthur Lewbel, Xun Lu, Liangjun Su Jan 2015

Specification Testing For Transformation Models With An Application To Generalized Accelerated Failure-Time Models, Arthur Lewbel, Xun Lu, Liangjun Su

Research Collection School Of Economics

This paper provides a nonparametric test of the specification of a transformation model. Specifically, we test whether an observable outcome Y is monotonic in the sum of a function of observable covariates X plus an unobservable error U. Transformation models of this form are commonly assumed in economics, including, e.g., standard specifications of duration models and hedonic pricing models. Our test statistic is asymptotically normal under local alternatives and consistent against nonparametric alternatives violating the implied restriction. Monte Carlo experiments show that our test performs well in finite samples. We apply our results to test for specifications of generalized accelerated …


Testing Linearity Using Power Transforms Of Regressors, Yae In Baek, Jin Seo Cho, Peter C. B. Phillips Jan 2015

Testing Linearity Using Power Transforms Of Regressors, Yae In Baek, Jin Seo Cho, Peter C. B. Phillips

Research Collection School Of Economics

We develop a method of testing linearity using power transforms of regressors, allowing for stationary processes and time trends. The linear model is a simplifying hypothesis that derives from the power transform model in three different ways, each producing its own identification problem. We call this modeling difficulty the trifold identification problem and show that it may be overcome using a test based on the quasi-likelihood ratio (QLR) statistic. More specifically, the QLR statistic may be approximated under each identification problem and the separate null approximations may be combined to produce a composite approximation that embodies the linear model hypothesis. …


On Bias In The Estimation Of Structural Break Points, Liang Jiang, Xiaohu Wang, Jun Yu Dec 2014

On Bias In The Estimation Of Structural Break Points, Liang Jiang, Xiaohu Wang, Jun Yu

Research Collection School Of Economics

Based on the Girsanov theorem, this paper obtains the exact Önite sample distribution of the maximum likelihood estimator of structural break points in a continuous time model. The exact Önite sample theory suggests that, in empirically realistic situations, there is a strong Önite sample bias in the estimator of structural break points. This property is shared by least squares estimator of both the absolute structural break point and the fractional structural break point in discrete time models. A simulation-based method based on the indirect estimation approach is proposed to reduce the bias both in continuous time and discrete time models. …


Structural Change Estimation In Time Series Regressions With Endogenous Variables, Junhui Qian, Liangjun Su Dec 2014

Structural Change Estimation In Time Series Regressions With Endogenous Variables, Junhui Qian, Liangjun Su

Research Collection School Of Economics

We propose to apply the group fused Lasso to estimate time series models with endogenous regressors and an unknown number of breaks. It can correctly determine the number of breaks and estimate the break dates asymptotically. Simulations and applications are given.


Testing The Martingale Hypothesis, Peter C. B. Phillips, Sainan Jin Dec 2014

Testing The Martingale Hypothesis, Peter C. B. Phillips, Sainan Jin

Research Collection School Of Economics

We propose new tests of the martingale hypothesis based on generalized versions of the Kolmogorov–Smirnov and Cramér–von Mises tests. The tests are distribution-free and allow for a weak drift in the null model. The methods do not require either smoothing parameters or bootstrap resampling for their implementation and so are well suited to practical work. The article develops limit theory for the tests under the null and shows that the tests are consistent against a wide class of nonlinear, nonmartingale processes. Simulations show that the tests have good finite sample properties in comparison with other tests particularly under conditional heteroscedasticity …


Norming Rates And Limit Theory For Some Time-Varying Coefficient Autoregressions, Offer Lieberman, Peter C. B. Phillips Nov 2014

Norming Rates And Limit Theory For Some Time-Varying Coefficient Autoregressions, Offer Lieberman, Peter C. B. Phillips

Research Collection School Of Economics

A time-varying autoregression is considered with a similarity-based coefficient and possible drift. It is shown that the random-walk model has a natural interpretation as the leading term in a small-sigma expansion of a similarity model with an exponential similarity function as its AR coefficient. Consistency of the quasi-maximum likelihood estimator of the parameters in this model is established, the behaviours of the score and Hessian functions are analysed and test statistics are suggested. A complete list is provided of the normalization rates required for the consistency proof and for the score and Hessian function standardization. A large family of unit …


Bound Estimator Of Hiv Prevalence: Application To Malawi, Tomoki Fujii, Denis H. Y. Leung Oct 2014

Bound Estimator Of Hiv Prevalence: Application To Malawi, Tomoki Fujii, Denis H. Y. Leung

Research Collection School Of Economics

To find lower and upper bounds of HIV prevalence in Malawi under mild and intuitive assumptions to assess the importance of the refusal issue in the estimation of HIV prevalence. Methods: We derive bounds based on the following two key assumptions: (i) Among those who have never taken an HIV test before, those who refuse to take an HIV test (hereafter “refusers”) have at least as much risk to be HIV positive as those who participate in the HIV test, and (ii) among the refusers, those who have a prior testing experience are at least as likely to be HIV …


Additive Nonparametric Regression In The Presence Of Endogenous Regressors, Deniz Ozabaci, Daniel J. Henderson, Liangjun Su Oct 2014

Additive Nonparametric Regression In The Presence Of Endogenous Regressors, Deniz Ozabaci, Daniel J. Henderson, Liangjun Su

Research Collection School Of Economics

In this article we consider nonparametric estimation of a structural equation model under full additivity constraint. We propose estimators for both the conditional mean and gradient which are consistent, asymptotically normal, oracle efficient, and free from the curse of dimensionality. Monte Carlo simulations support the asymptotic developments. We employ a partially linear extension of our model to study the relationship between child care and cognitive outcomes. Some of our (average) results are consistent with the literature (e.g., negative returns to child care when mothers have higher levels of education). However, as our estimators allow for heterogeneity both across and within …


A New Hedonic Regression For Real Estate Prices Applied To The Singapore Residential Market, Jiang Liang, Peter C. B. Phillips, Jun Yu Oct 2014

A New Hedonic Regression For Real Estate Prices Applied To The Singapore Residential Market, Jiang Liang, Peter C. B. Phillips, Jun Yu

Research Collection School Of Economics

This paper develops a new hedonic method for constructing a real estate price index that utilizes all transaction price information that encompasses both single-sale and repeat-sale properties. The new method is less prone to specification errors than standard hedonic methods and uses all available data. Like the Case-Shiller repeat-sales method, the new method has the advantage of being computationally efficient. In an empirical analysis of the methodology, we fit the model to all transaction prices for private residential property holdings in Singapore between Q1 1995 and Q2 2014, covering several periods of major price fluctuation and changes in government macro …


Intraday Periodicity Adjustments Of Transaction Duration And Their Effects On High-Frequency Volatility Estimation, Yiu Kuen Tse, Yingjie Dong Sep 2014

Intraday Periodicity Adjustments Of Transaction Duration And Their Effects On High-Frequency Volatility Estimation, Yiu Kuen Tse, Yingjie Dong

Research Collection School Of Economics

We study two methods of adjusting for intraday periodicity of high-frequency financial data: the well-known Duration Adjustment (DA) method and the recently proposed Time Transformation (TT) method (Wu (2012)). We examine the effects of these adjustments on the estimation of intraday volatility using the Autoregressive Conditional Duration-Integrated Conditional Variance (ACD-ICV) method of Tse and Yang (2012). We find that daily volatility estimates are not sensitive to intraday periodicity adjustment. However, intraday volatility is found to have a weaker U-shaped volatility smile and a biased trough if intraday periodicity adjustment is not applied. In addition, adjustment taking account of trades with …


Asymptotic Distribution And Finite-Sample Bias Correction Of Qml Estimators For Spatial Dependence Model, Shew Fan Liu, Zhenlin Yang Sep 2014

Asymptotic Distribution And Finite-Sample Bias Correction Of Qml Estimators For Spatial Dependence Model, Shew Fan Liu, Zhenlin Yang

Research Collection School Of Economics

In studying the asymptotic and finite-sample properties of quasi-maximum likelihood (QML) estimators for the spatial linear regression models, much attention has been paid to the spatial lag dependence (SLD) model; little has been given to its companion, the spatial error dependence (SED) model. In particular, the effect of spatial dependence on the convergence rate of the QML estimators has not been formally studied, and methods for correcting finite-sample bias of the QML estimators have not been given. This paper fills in these gaps. Of the two, bias correction is particularly important to the application of this model. Contrary to the …


Initial-Condition Free Estimation Of Fixed Effects Dynamic Panel Data Models, Zhenlin Yang Sep 2014

Initial-Condition Free Estimation Of Fixed Effects Dynamic Panel Data Models, Zhenlin Yang

Research Collection School Of Economics

It is well known that (quasi) MLE of dynamic panel data (DPD) models with short panels depends on the assumptions on the initial values; ignoring them or a wrong treatment of them will result in inconsistency or serious bias. This paper introduces a initial-condition free method for estimating the fixed-effects DPD models, through as simple modification of the quasi-score. An outer-product-of-gradients (OPG) method is also proposed for robust inference. The MLE of Hsiao, Pesaran and Tahmiscioglu (2002, Journal of Econometrics), where the initial observations are modeled, is extended to quasi MLE and an OPG method is proposed for robust inference. …


Modified Qml Estimation Of Spatial Autoregressive Models With Unknown Heteroskedasticity And Nonnormality, Shew Fan Liu, Zhenlin Yang Sep 2014

Modified Qml Estimation Of Spatial Autoregressive Models With Unknown Heteroskedasticity And Nonnormality, Shew Fan Liu, Zhenlin Yang

Research Collection School Of Economics

In the presence of heteroskedasticity, Lin and Lee (2010) show that the quasi maximum likelihood (QML) estimators of spatial autoregressive models (SAR) can be inconsistent as a ‘necessary’ condition for consistency can be violated, and thus propose robust GMM estimators for the model. In this paper, we first show that this condition may hold in many practical situations and when it does the regular QML estimators can be consistent.In cases where this condition is violated, we propose a modified QML estimation method robust against heteroskedasticity of unknown form. In both cases, asymptotic distributions of the estimators are derived, and methods …


Testing Conditional Independence Via Empirical Likelihood, Liangjun Su, Halbert White Sep 2014

Testing Conditional Independence Via Empirical Likelihood, Liangjun Su, Halbert White

Research Collection School Of Economics

We construct two classes of smoothed empirical likelihood ratio tests for the conditional independence hypothesis by writing the null hypothesis as an infinite collection of conditional moment restrictions indexed by a nuisance parameter. One class is based on the CDF; another is based on smoother functions. We show that the test statistics are asymptotically normal under the null hypothesis and a sequence of Pitman local alternatives. We also show that the tests possess an asymptotic optimality property in terms of average power. Simulations suggest that the tests are well behaved in finite samples. Applications to some economic and financial time …


Identifying Latent Structures In Panel Data, Liangjun Su, Zhentao Shi, Peter C. B. Phillips Aug 2014

Identifying Latent Structures In Panel Data, Liangjun Su, Zhentao Shi, Peter C. B. Phillips

Research Collection School Of Economics

This paper provides a novel mechanism for identifying and estimating latent group structures in panel data using penalized regression techniques. We focus on linear models where the slope parameters are heterogeneous across groups but homogenous within a group and the group membership is unknown. Two approaches are considered — penalized least squares (PLS) for models without endogenous regressors, and penalized GMM (PGMM) for models with endogeneity. In both cases we develop a new variant of Lasso called classifier-Lasso (C-Lasso) that serves to shrink individual coefficients to the unknown group-specific coefficients. C-Lasso achieves simultaneous classification and consistent estimation in a single …