Simple moment-based tests for value-at-risk models and discrete distribution
Author
Abstract
Suggested Citation
Download full text from publisher
References listed on IDEAS
- Bertrand Candelon & Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2011.
"Backtesting Value-at-Risk: A GMM Duration-Based Test,"
Journal of Financial Econometrics, Oxford University Press, vol. 9(2), pages 314-343, Spring.
- Gilbert COLLETAZ & Christophe HURLIN & Sessi TOKPAVI, 2008. "Backtesting Value-at-Risk: A GMM Duration-Based Test," LEO Working Papers / DR LEO 266, Orleans Economics Laboratory / Laboratoire d'Economie d'Orleans (LEO), University of Orleans.
- Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2008. "Backtesting Value-at-Risk : A GMM Duration-based Test," Post-Print halshs-00363165, HAL.
- Candelon, B. & Colletaz, G. & Hurlin, C. & Tokpavi, S., 2009. "Backtesting value-at-risk : a GMM duration-based test," Research Memorandum 062, Maastricht University, Maastricht Research School of Economics of Technology and Organization (METEOR).
- Gilbert COLLETAZ & Christophe HURLIN & Sessi TOKPAVI, 2009. "Backtesting Value-at-Risk: A GMM Duration-Based Test," LEO Working Papers / DR LEO 265, Orleans Economics Laboratory / Laboratoire d'Economie d'Orleans (LEO), University of Orleans.
- Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2008. "Backtesting Value-at-Risk: A GMM Duration-Based Test," Post-Print halshs-00364793, HAL.
- Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2008. "Backtesting Value-at-Risk : A GMM Duration-based Test," Post-Print halshs-00363168, HAL.
- Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2008. "Backtesting Value-at-Risk: A GMM Duration-Based Test," Post-Print halshs-00364797, HAL.
- Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2008. "Backtesting Value-at-Risk : A GMM Duration-based Test," Post-Print halshs-00363146, HAL.
- Christophe Hurlin & Gilbert Colletaz & Sessi Tokpavi & Bertrand Candelon, 2008. "Backtesting Value-at-Risk: A GMM Duration-Based Test," Working Papers halshs-00329495, HAL.
- Gilbert Colletaz & Christophe Hurlin & Sessi Tokpavi, 2008. "Backtesting Value-at-Risk: A GMM Duration-Based-Test," Post-Print halshs-00364796, HAL.
- Gianna Boero & Jeremy Smith & Kenneth Wallis, 2005.
"The Sensitivity of Chi-Squared Goodness-of-Fit Tests to the Partitioning of Data,"
Econometric Reviews, Taylor & Francis Journals, vol. 23(4), pages 341-370.
- Boero, Gianna & Smith, Jeremy & Wallis, Kenneth F., 2004. "Sensitivity of the chi-squared goodness-of-fit test to the partitioning of data," Economic Research Papers 269588, University of Warwick - Department of Economics.
- Boero, Gianna & Smith, Jeremy & Wallis, Kenneth F, 2004. "Sensitivity of the Chi-Squared Goodness-of-Fit Test to the Partitioning of Data," The Warwick Economics Research Paper Series (TWERPS) 694, University of Warwick, Department of Economics.
- James D. Hamilton & Oscar Jorda, 2002.
"A Model of the Federal Funds Rate Target,"
Journal of Political Economy, University of Chicago Press, vol. 110(5), pages 1135-1167, October.
- James D. Hamilton & Oscar Jorda, "undated". "A model for the federal funds rate target," Department of Economics 99-07, California Davis - Department of Economics.
- James D. Hamilton & Oscar Jorda, 2000. "A Model for the Federal Funds Rate Target," NBER Working Papers 7847, National Bureau of Economic Research, Inc.
- Oscar Jorda & James D. Hamilton, 2003. "A model for the federal funds rate target," Working Papers 176, University of California, Davis, Department of Economics.
- Jean‐Marie Dufour & Lynda Khalaf & Marie‐Claude Beaulieu, 2003.
"Exact Skewness–Kurtosis Tests for Multivariate Normality and Goodness‐of‐Fit in Multivariate Regressions with Application to Asset Pricing Models,"
Oxford Bulletin of Economics and Statistics, Department of Economics, University of Oxford, vol. 65(s1), pages 891-906, December.
- DUFOUR, Jean-Marie & KHALAF, Lynda & BEAULIEU, Marie-Claude, 2003. "Exact Skewness-Kurtosis Tests for Multivariate Normality and Goodness-of-fit in Multivariate Regressions with Application to Asset Pricing Models," Cahiers de recherche 2003-09, Universite de Montreal, Departement de sciences economiques.
- DUFOUR, Jean-Marie & KHALAF, Lynda & BEAULIEU, Marie-Claude, 2003. "Exact Skewness-Kurtosis Tests for Multivariate Normality and Goodness-of-Fit in Multivariate Regressions with Application to Asset Pricing Models," Cahiers de recherche 07-2003, Centre interuniversitaire de recherche en économie quantitative, CIREQ.
- Jean-Marie Dufour & Lynda Khalaf & Marie-Claude Beaulieu, 2003. "Exact skewness-kurtosis tests for multivariate normality and goodness-of-fit in multivariate regressions with application to asset pricing models," CIRANO Working Papers 2003s-33, CIRANO.
- West, Kenneth D, 1996.
"Asymptotic Inference about Predictive Ability,"
Econometrica, Econometric Society, vol. 64(5), pages 1067-1084, September.
- West, K.D., 1994. "Asymptotic Inference About Predictive Ability," Working papers 9417, Wisconsin Madison - Social Systems.
- Kenneth D. West, 1994. "Asymptotic Inference About Predictive Ability," Macroeconomics 9410002, University Library of Munich, Germany.
- Mora, Juan & Moro-Egido, Ana I., 2008. "On specification testing of ordered discrete choice models," Journal of Econometrics, Elsevier, vol. 143(1), pages 191-205, March.
- Sangjoon Kim & Neil Shephard & Siddhartha Chib, 1998.
"Stochastic Volatility: Likelihood Inference and Comparison with ARCH Models,"
The Review of Economic Studies, Review of Economic Studies Ltd, vol. 65(3), pages 361-393.
- Sangjoon Kim, Neil Shephard & Siddhartha Chib, "undated". "Stochastic volatility: likelihood inference and comparison with ARCH models," Economics Papers W26, revised version of W, Economics Group, Nuffield College, University of Oxford.
- Sangjoon Kim & Neil Shephard, 1994. "Stochastic volatility: likelihood inference and comparison with ARCH models," Economics Papers 3., Economics Group, Nuffield College, University of Oxford.
- Sangjoon Kim & Neil Shephard & Siddhartha Chib, 1996. "Stochastic Volatility: Likelihood Inference And Comparison With Arch Models," Econometrics 9610002, University Library of Munich, Germany.
- Fiorentini, Gabriele & Sentana, Enrique & Calzolari, Giorgio, 2004.
"On the validity of the Jarque-Bera normality test in conditionally heteroskedastic dynamic regression models,"
Economics Letters, Elsevier, vol. 83(3), pages 307-312, June.
- Gabriele Fiorentini & Enrique Sentana & Giorgio Calzolari, 2003. "On the Validity of the Jarque-Bera Normality Test in Conditionally Heteroskedastic Dynamic Regression Models," Working Papers wp2003_0306, CEMFI.
- Javier Mencía & Enrique Sentana, 2012.
"Distributional Tests in Multivariate Dynamic Models with Normal and Student-t Innovations,"
The Review of Economics and Statistics, MIT Press, vol. 94(1), pages 133-152, February.
- Javier Mencía & Enrique Sentana, 2008. "Distributional Tests in Multivariate Dynamic Models with Normal and Student t Innovations," Working Papers wp2008_0804, CEMFI.
- Javier Mencía & Enrique Sentana, 2009. "Distributional tests in multivariate dynamic models with Normal and Student t innovations," Working Papers 0929, Banco de España.
- Jin-Chuan Duan, 2004. "A Specification Test for Time Series Models by a Normality," Econometric Society 2004 North American Winter Meetings 467, Econometric Society.
- Amengual, Dante & Fiorentini, Gabriele & Sentana, Enrique, 2013.
"Sequential estimation of shape parameters in multivariate dynamic models,"
Journal of Econometrics, Elsevier, vol. 177(2), pages 233-249.
- Dante Amengual & Gabriele Fiorentini & Enrique Sentana, 2012. "Sequential Estimation of Shape Parameters in Multivariate Dynamic Models," Working Papers wp2012_1201, CEMFI.
- Bo Li, 2009. "Asymptotically Distribution-Free Goodness-of-Fit Testing: A Unifying View," Econometric Reviews, Taylor & Francis Journals, vol. 28(6), pages 632-657.
- Escanciano, J. C. & Olmo, J., 2007. "Estimation risk effects on backtesting for parametric value-at-risk models," Working Papers 07/11, Department of Economics, City University London.
- Newey, Whitney & West, Kenneth, 2014.
"A simple, positive semi-definite, heteroscedasticity and autocorrelation consistent covariance matrix,"
Applied Econometrics, Russian Presidential Academy of National Economy and Public Administration (RANEPA), vol. 33(1), pages 125-132.
- Newey, Whitney K & West, Kenneth D, 1987. "A Simple, Positive Semi-definite, Heteroskedasticity and Autocorrelation Consistent Covariance Matrix," Econometrica, Econometric Society, vol. 55(3), pages 703-708, May.
- Whitney K. Newey & Kenneth D. West, 1986. "A Simple, Positive Semi-Definite, Heteroskedasticity and AutocorrelationConsistent Covariance Matrix," NBER Technical Working Papers 0055, National Bureau of Economic Research, Inc.
- Jushan Bai, 2003. "Testing Parametric Conditional Distributions of Dynamic Models," The Review of Economics and Statistics, MIT Press, vol. 85(3), pages 531-549, August.
- Chen, Yi-Ting, 2012. "A simple approach to standardized-residuals-based higher-moment tests," Journal of Empirical Finance, Elsevier, vol. 19(4), pages 427-453.
- Skeels, Christopher L. & Vella, Francis, 1999. "A Monte Carlo investigation of the sampling behavior of conditional moment tests in Tobit and Probit models," Journal of Econometrics, Elsevier, vol. 92(2), pages 275-294, October.
Citations
Citations are extracted by the CitEc Project, subscribe to its RSS feed for this item.
Cited by:
- Denis Pelletier & Wei Wei, 2016. "The Geometric-VaR Backtesting Method," Journal of Financial Econometrics, Oxford University Press, vol. 14(4), pages 725-745.
Most related items
These are the items that most often cite the same works as this one and are cited by the same works as this one.- Bontemps, Christian, 2013. "Moment-Based Tests for Discrete Distributions," IDEI Working Papers 772, Institut d'Économie Industrielle (IDEI), Toulouse, revised Oct 2014.
- Christian Bontemps, 2019.
"Moment-Based Tests under Parameter Uncertainty,"
The Review of Economics and Statistics, MIT Press, vol. 101(1), pages 146-159, March.
- Bontemps, Christian, 2018. "Moment-based tests under parameter uncertainty," IDEI Working Papers 18-883, Institut d'Économie Industrielle (IDEI), Toulouse.
- Christian Bontemps, 2019. "Moment-Based Tests under Parameter Uncertainty," Post-Print hal-02004687, HAL.
- Christian Bontemps & Nour Meddahi, 2012.
"Testing distributional assumptions: A GMM aproach,"
Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 27(6), pages 978-1012, September.
- N. Meddahi & C. Bontemps, 2004. "Testing Distributional Assumptions: A GMM Approach," Econometric Society 2004 North American Winter Meetings 487, Econometric Society.
- Christian Bontemps & Nour Meddahi, 2012. "Testing distributional assumptions: A GMM aproach," Post-Print hal-02875123, HAL.
- Bontemps, Christian & Meddahi, Nour, 2007. "Testing Distributional Assumptions: A GMM Approach," IDEI Working Papers 486, Institut d'Économie Industrielle (IDEI), Toulouse.
- Jonas Dovern & Hans Manner, 2020.
"Order‐invariant tests for proper calibration of multivariate density forecasts,"
Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 35(4), pages 440-456, June.
- Jonas Dovern & Hans Manner, 2018. "Order Invariant Tests for Proper Calibration of Multivariate Density Forecasts," CESifo Working Paper Series 7023, CESifo.
- Jonas Dovern & Hans Manner, 2018. "Order Invariant Tests for Proper Calibration of Multivariate Density Forecasts," Graz Economics Papers 2018-09, University of Graz, Department of Economics.
- Corradi, Valentina & Swanson, Norman R., 2004.
"Some recent developments in predictive accuracy testing with nested models and (generic) nonlinear alternatives,"
International Journal of Forecasting, Elsevier, vol. 20(2), pages 185-199.
- Valentina Corradi & Norman Swanson, 2003. "Some Recent Developments in Predictive Accuracy Testing With Nested Models and (Generic) Nonlinear Alternatives," Departmental Working Papers 200316, Rutgers University, Department of Economics.
- Gabriele Fiorentini & Enrique Sentana, 2021.
"Specification tests for non‐Gaussian maximum likelihood estimators,"
Quantitative Economics, Econometric Society, vol. 12(3), pages 683-742, July.
- Gabriele Fiorentini & Enrique Sentana, 2018. "Specification tests for non-Gaussian maximum likelihood estimators," Working Paper series 18-22, Rimini Centre for Economic Analysis.
- Gabriele Fiorentini & Enrique Sentana, 2018. "Specification tests for non-Gaussian maximum likelihood estimators," Econometrics Working Papers Archive 2018_05, Universita' degli Studi di Firenze, Dipartimento di Statistica, Informatica, Applicazioni "G. Parenti".
- Sentana, Enrique & Fiorentini, Gabriele, 2018. "Specification tests for non-Gaussian maximum likelihood estimators," CEPR Discussion Papers 12934, C.E.P.R. Discussion Papers.
- Gabriele Fiorentini & Enrique Sentana, 2018. "Specification Tests for Non-Gaussian Maximum Likelihood Estimators," Working Papers wp2018_1804, CEMFI.
- Sarno, Lucio & Thornton, Daniel L & Valente, Giorgio, 2005.
"Federal Funds Rate Prediction,"
Journal of Money, Credit and Banking, Blackwell Publishing, vol. 37(3), pages 449-471, June.
- Sarno, Lucio & Daniel l Thornton & Giorgio Valente, 2003. "Federal Funds Rate Prediction," Royal Economic Society Annual Conference 2003 183, Royal Economic Society.
- Lucio Sarno & Daniel L. Thornton & Giorgio Valente, 2004. "Federal funds rate prediction," Working Papers 2002-005, Federal Reserve Bank of St. Louis.
- Sarno, Lucio & Thornton, Daniel L & Valente, Giorgio, 2004. "Federal Funds Rate Prediction," CEPR Discussion Papers 4587, C.E.P.R. Discussion Papers.
- Rossi, Barbara & Sekhposyan, Tatevik, 2013.
"Conditional predictive density evaluation in the presence of instabilities,"
Journal of Econometrics, Elsevier, vol. 177(2), pages 199-212.
- Barbara Rossi & Tatevik Sekhposyan, 2013. "Conditional predictive density evaluation in the presence of instabilities," Economics Working Papers 1368, Department of Economics and Business, Universitat Pompeu Fabra.
- Barbara Rossi & Tatevik Sehkposyan, 2013. "Conditional Predictive Density Evaluation in the Presence of Instabilities," Working Papers 688, Barcelona School of Economics.
- Bontemps, Christian & Meddahi, Nour, 2005.
"Testing normality: a GMM approach,"
Journal of Econometrics, Elsevier, vol. 124(1), pages 149-186, January.
- Christian Bontemps & Nour Meddahi, 2002. "Testing Normality: A GMM Approach," CIRANO Working Papers 2002s-63, CIRANO.
- Christian Bontemps & Nour Meddahi, 2005. "Testing normality: a GMM approach," Post-Print hal-02875105, HAL.
- BONTEMPS, Christian & MEDDAHI, Nour, 2002. "Testing Normality : A GMM Approach," Cahiers de recherche 2002-14, Universite de Montreal, Departement de sciences economiques.
- Christian BONTEMPS & Nour MEDDAHI, 2002. "Testing Normality : A Gmm Approach," Cahiers de recherche 14-2002, Centre interuniversitaire de recherche en économie quantitative, CIREQ.
- Kheifets, Igor & Velasco, Carlos, 2017.
"New goodness-of-fit diagnostics for conditional discrete response models,"
Journal of Econometrics, Elsevier, vol. 200(1), pages 135-149.
- Igor Kheifets & Carlos Velasco, 2013. "New Goodness-of-fit Diagnostics for Conditional Discrete Response Models," Cowles Foundation Discussion Papers 1924, Cowles Foundation for Research in Economics, Yale University.
- Igor Kheifets & Carlos Velasco, 2017. "New Goodness-of-fit Diagnostics for Conditional Discrete Response Models," Cowles Foundation Discussion Papers 1924R, Cowles Foundation for Research in Economics, Yale University.
- Fabian Krüger & Todd E. Clark & Francesco Ravazzolo, 2017.
"Using Entropic Tilting to Combine BVAR Forecasts With External Nowcasts,"
Journal of Business & Economic Statistics, Taylor & Francis Journals, vol. 35(3), pages 470-485, July.
- Fabian Kr ger & Todd E. Clark & Francesco Ravazzolo, 2015. "Using Entropic Tilting to Combine BVAR Forecasts with External Nowcasts," Working Papers No 8/2015, Centre for Applied Macro- and Petroleum economics (CAMP), BI Norwegian Business School.
- Todd E. Clark & Fabian Krueger & Francesco Ravazzolo, 2015. "Using Entropic Tilting to Combine BVAR Forecasts with External Nowcasts," Working Papers (Old Series) 1439, Federal Reserve Bank of Cleveland.
- Krüger, Fabian & Clark, Todd E. & Ravazzolo, Francesco, 2015. "Using Entropic Tilting to Combine BVAR Forecasts with External Nowcasts," VfS Annual Conference 2015 (Muenster): Economic Development - Theory and Policy 113077, Verein für Socialpolitik / German Economic Association.
- Igor Kheifets & Carlos Velasco, 2012.
"Model Adequacy Checks for Discrete Choice Dynamic Models,"
Working Papers
w0170, New Economic School (NES).
- Igor Kheifets & Carlos Velasco, 2012. "Model Adequacy Checks for Discrete Choice Dynamic Models," Working Papers w0170, Center for Economic and Financial Research (CEFIR).
- Chen, Yi-Ting, 2012. "A simple approach to standardized-residuals-based higher-moment tests," Journal of Empirical Finance, Elsevier, vol. 19(4), pages 427-453.
- Cavit Pakel & Neil Shephard & Kevin Sheppard, 2009.
"Nuisance parameters, composite likelihoods and a panel of GARCH models,"
Economics Papers
2009-W12, Economics Group, Nuffield College, University of Oxford.
- Cavit Pakel & Neil Shephard & Kevin Sheppard, 2009. "Nuisance parameters, composite likelihoods and a panel of GARCH models," OFRC Working Papers Series 2009fe03, Oxford Financial Research Centre.
- Neil Shephard & Kevin Sheppard, 2009. "Nuisance parameters, composite likelihoods and a panel of GARCH models," Economics Series Working Papers 458, University of Oxford, Department of Economics.
- Raggi, Davide & Bordignon, Silvano, 2012.
"Long memory and nonlinearities in realized volatility: A Markov switching approach,"
Computational Statistics & Data Analysis, Elsevier, vol. 56(11), pages 3730-3742.
- S. Bordignon & D. Raggi, 2010. "Long memory and nonlinearities in realized volatility: a Markov switching approach," Working Papers 694, Dipartimento Scienze Economiche, Universita' di Bologna.
- Graham Elliott & Ivana Komunjer & Allan Timmermann, 2008.
"Biases in Macroeconomic Forecasts: Irrationality or Asymmetric Loss?,"
Journal of the European Economic Association, MIT Press, vol. 6(1), pages 122-157, March.
- Allan Timmermann & Graham Elliott & Ivana Komunjer, 2004. "Biases in Macroeconomic Forecasts: Irrationality or Asymmetric Loss?," Econometric Society 2004 North American Summer Meetings 601, Econometric Society.
- Graham Elliott & Ivana Komunjer & Allan Timmermann, 2005. "Biases In Macroeconomic Forecasts: Irrationality Or Asymmetric Loss?," CAMA Working Papers 2005-14, Centre for Applied Macroeconomic Analysis, Crawford School of Public Policy, The Australian National University.
- Richard H. Clarida & Lucio Sarno & Mark P. Taylor & Giorgio Valente, 2006.
"The Role of Asymmetries and Regime Shifts in the Term Structure of Interest Rates,"
The Journal of Business, University of Chicago Press, vol. 79(3), pages 1193-1224, May.
- Taylor, Mark & Clarida, Richard & Sarno, Lucio & Valente, Giorgio, 2005. "The Role of Asymmetries and Regime Shifts in the Term Structure of Interest Rates," CEPR Discussion Papers 4835, C.E.P.R. Discussion Papers.
- Fernandes, Marcelo & Grammig, Joachim, 2005.
"Nonparametric specification tests for conditional duration models,"
Journal of Econometrics, Elsevier, vol. 127(1), pages 35-68, July.
- Fernandes, M. & Grammig, J., 2000. "Non-Parametric Specification Tests for Conditional Duration Models," Economics Working Papers eco2000/4, European University Institute.
- Marcelo Fernandes & Joachim Grammig, 2000. "Non-Parametric Specification Tests For Conditional Duration Models," Computing in Economics and Finance 2000 40, Society for Computational Economics.
- Fernandes, Marcelo & Grammig, Joachim, 2003. "Nonparametric specification tests for conditional duration models," FGV EPGE Economics Working Papers (Ensaios Economicos da EPGE) 502, EPGE Brazilian School of Economics and Finance - FGV EPGE (Brazil).
- Lahiri, Kajal & Yang, Liu, 2013.
"Forecasting Binary Outcomes,"
Handbook of Economic Forecasting, in: G. Elliott & C. Granger & A. Timmermann (ed.), Handbook of Economic Forecasting, edition 1, volume 2, chapter 0, pages 1025-1106,
Elsevier.
- Kajal Lahiri & Liu Yang, 2012. "Forecasting Binary Outcomes," Discussion Papers 12-09, University at Albany, SUNY, Department of Economics.
- Diaa Noureldin & Neil Shephard & Kevin Sheppard, 2012.
"Multivariate high‐frequency‐based volatility (HEAVY) models,"
Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 27(6), pages 907-933, September.
- Diaa Noureldin & Neil Shephard & Kevin Sheppard, 2011. "Multivariate High-Frequency-Based Volatility (HEAVY) Models," Economics Series Working Papers 533, University of Oxford, Department of Economics.
- Diaa Noureldin & Neil Shephard & Kevin Sheppard, 2011. "Multivariate High-Frequency-Based Volatility (HEAVY) Models," Economics Papers 2011-W01, Economics Group, Nuffield College, University of Oxford.
More about this item
Keywords
moment-based tests; parameter uncertainty; discrete distributions; value-at-risk; backtesting;All these keywords.
JEL classification:
- C12 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Hypothesis Testing: General
Statistics
Access and download statisticsCorrections
All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:tse:wpaper:28749. See general information about how to correct material in RePEc.
If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.
If CitEc recognized a bibliographic reference but did not link an item in RePEc to it, you can help with this form .
If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: the person in charge (email available below). General contact details of provider: https://edirc.repec.org/data/tsetofr.html .
Please note that corrections may take a couple of weeks to filter through the various RePEc services.