IDEAS home Printed from https://ideas.repec.org/p/iza/izadps/dp5175.html
   My bibliography  Save this paper

From Estimation Results to Stylized Facts: Twelve Recommendations for Empirical Research in International Activities of Heterogeneous Firms

Author

Listed:
  • Wagner, Joachim

    (Leuphana University Lüneburg)

Abstract

Heterogeneous firms are at the heart of both the New New International Trade Theory and the Micro-econometrics of International Firm Activities. One important aim of micro-econometric studies is to uncover stylized facts that hold over space and time, and that can both inspire theoretical models that are based on “realistic” assumptions, and inform policy debates in an evidence-based way. Which results from the thousands of empirical estimates reported in the literature on the micro-econometrics of international firm activities do we consider as convincing? Based on my own experience from the last twenty years I use the opportunity of this lecture to make twelve recommendations that, hopefully, will help to find the right way on the thorny road from estimation results to stylized facts. I will deal with the following topics: comparisons of means vs. comparisons of distributions; extremely different firms, or outliers; unobserved heterogeneity; simultaneous occurrence of differences across quantiles, outliers, and unobserved heterogeneity; heterogeneous effects of international firm activities on firm performance; replication; within-study replication by international research teams; meta-analysis; and talking to practitioners.

Suggested Citation

  • Wagner, Joachim, 2010. "From Estimation Results to Stylized Facts: Twelve Recommendations for Empirical Research in International Activities of Heterogeneous Firms," IZA Discussion Papers 5175, Institute of Labor Economics (IZA).
    • Handle: RePEc:iza:izadps:dp5175
    as

    Download full text from publisher

    File URL: https://docs.iza.org/dp5175.pdf
    Download Restriction: no
    ---><---

    Other versions of this item:

    References listed on IDEAS

    as
    1. Wagner, Joachim, 2002. "The causal effects of exports on firm size and labor productivity: first evidence from a matching approach," Economics Letters, Elsevier, vol. 77(2), pages 287-292, October.
    2. Joachim Wagner, 2008. "Export Entry, Export Exit and Productivity in German Manufacturing Industries," International Journal of the Economics of Business, Taylor & Francis Journals, vol. 15(2), pages 169-180.
    3. Helmut Fryges & Joachim Wagner, 2021. "Exports and Productivity Growth — First Evidence from a Continuous Treatment Approach," World Scientific Book Chapters, in: Joachim Wagner (ed.), MICROECONOMETRIC STUDIES OF FIRMS’ IMPORTS AND EXPORTS Advanced Methods of Analysis and Evidence from German Enterprises, chapter 6, pages 57-86, World Scientific Publishing Co. Pte. Ltd..
    4. Verardi Vincenzo & Wagner Joachim, 2011. "Robust Estimation of Linear Fixed Effects Panel Data Models with an Application to the Exporter Productivity Premium," Journal of Economics and Statistics (Jahrbuecher fuer Nationaloekonomie und Statistik), De Gruyter, vol. 231(4), pages 546-557, August.
    5. Chad Syverson, 2011. "What Determines Productivity?," Journal of Economic Literature, American Economic Association, vol. 49(2), pages 326-365, June.
    6. Joachim Wagner, 2016. "Exports and Productivity: A Survey of the Evidence from Firm Level Data," World Scientific Book Chapters, in: Microeconometrics of International Trade, chapter 1, pages 3-41, World Scientific Publishing Co. Pte. Ltd..
    7. Pedro Martins & Yong Yang, 2009. "The impact of exporting on firm productivity: a meta-analysis of the learning-by-exporting hypothesis," Review of World Economics (Weltwirtschaftliches Archiv), Springer;Institut für Weltwirtschaft (Kiel Institute for the World Economy), vol. 145(3), pages 431-445, October.
    8. Helmut Fryges & Joachim Wagner, 2016. "Exports and Profitability — First Evidence for German Manufacturing Firms," World Scientific Book Chapters, in: Microeconometrics of International Trade, chapter 7, pages 245-277, World Scientific Publishing Co. Pte. Ltd..
    9. Moshe Buchinsky, 1998. "Recent Advances in Quantile Regression Models: A Practical Guideline for Empirical Research," Journal of Human Resources, University of Wisconsin Press, vol. 33(1), pages 88-126.
    10. Henk Kox & Hugo Rojas-Romagosa, 2010. "Exports and Productivity Selection Effects for Dutch Firms," De Economist, Springer, vol. 158(3), pages 295-322, September.
    11. Koenker, Roger, 2004. "Quantile regression for longitudinal data," Journal of Multivariate Analysis, Elsevier, vol. 91(1), pages 74-89, October.
    12. Alan S. Blinder, 1990. "Learning by Asking Those Who Are Doing," Eastern Economic Journal, Eastern Economic Association, vol. 16(4), pages 297-306, Oct-Dec.
    13. Delgado, Miguel A. & Farinas, Jose C. & Ruano, Sonia, 2002. "Firm productivity and export markets: a non-parametric approach," Journal of International Economics, Elsevier, vol. 57(2), pages 397-422, August.
    14. Alexander Vogel & Joachim Wagner, 2016. "Exports and Profitability — First Evidence for German Business Services Enterprises," World Scientific Book Chapters, in: Microeconometrics of International Trade, chapter 8, pages 279-310, World Scientific Publishing Co. Pte. Ltd..
    15. Joachim Wagner, 2009. "Exporte und Firmenerfolg: Welche Firmen profitieren wie vom internationalen Handel?," AStA Wirtschafts- und Sozialstatistisches Archiv, Springer;Deutsche Statistische Gesellschaft - German Statistical Society, vol. 3(2), pages 109-122, October.
    16. Koenker,Roger, 2005. "Quantile Regression," Cambridge Books, Cambridge University Press, number 9780521845731.
    17. Richard B. Freeman & Kathryn L. Shaw, 2009. "International Differences in the Business Practices and Productivity of Firms," NBER Books, National Bureau of Economic Research, Inc, number free07-1, March.
    18. Elhanan Helpman, 2006. "Trade, FDI, and the Organization of Firms," Journal of Economic Literature, American Economic Association, vol. 44(3), pages 589-630, September.
    19. Francesco Serti & Chiara Tomasi, 2009. "Self-selection along different export and import markets," LEM Papers Series 2009/18, Laboratory of Economics and Management (LEM), Sant'Anna School of Advanced Studies, Pisa, Italy.
    20. Daniel S. Hamermesh, 2007. "Replication in Economics," NBER Working Papers 13026, National Bureau of Economic Research, Inc.
    21. Pedro S. Martins & Yong Yang, 2007. "The Impact of Exporting on Firm Productivity: A Meta-Analysis," Working Papers 6, Queen Mary, University of London, School of Business and Management, Centre for Globalisation Research.
    22. Mark J. Koetse & Henri L.F. de Groot & Raymond J.G.M. Florax, 2009. "A Meta-Analysis of the Investment-Uncertainty Relationship," Southern Economic Journal, John Wiley & Sons, vol. 76(1), pages 283-306, July.
    23. James J. Heckman, 2001. "Micro Data, Heterogeneity, and the Evaluation of Public Policy: Nobel Lecture," Journal of Political Economy, University of Chicago Press, vol. 109(4), pages 673-748, August.
    24. Yasar, Mahmut & Morrison Paul, Catherine J., 2007. "International linkages and productivity at the plant level: Foreign direct investment, exports, imports and licensing," Journal of International Economics, Elsevier, vol. 71(2), pages 373-388, April.
    25. Temouri, Yama & Vogel, Alexander & Wagner, Joachim, 2013. "Self-selection into export markets by business services firms – Evidence from France, Germany and the United Kingdom," Structural Change and Economic Dynamics, Elsevier, vol. 25(C), pages 146-158.
    26. B. D. McCullough & H. D. Vinod, 2003. "Verifying the Solution from a Nonlinear Solver: A Case Study," American Economic Review, American Economic Association, vol. 93(3), pages 873-892, June.
    27. Buchinsky, Moshe, 1994. "Changes in the U.S. Wage Structure 1963-1987: Application of Quantile Regression," Econometrica, Econometric Society, vol. 62(2), pages 405-458, March.
    28. Jens M. Arnold & Katrin Hussinger, 2010. "Exports versus FDI in German Manufacturing: Firm Performance and Participation in International Markets," Review of International Economics, Wiley Blackwell, vol. 18(4), pages 595-606, September.
    29. Nicholas Bloom & John Van Reenen, 2010. "Why Do Management Practices Differ across Firms and Countries?," Journal of Economic Perspectives, American Economic Association, vol. 24(1), pages 203-224, Winter.
    30. Girma, Sourafel & Greenaway, David & Kneller, Richard, 2003. "Export market exit and performance dynamics: a causality analysis of matched firms," Economics Letters, Elsevier, vol. 80(2), pages 181-187, August.
    31. Powell, David & Wagner, Joachim, 2010. "The Exporter Productivity Premium along the Productivity Distribution: First Evidence from a Quantile Regression Approach for Fixed Effects Panel Data Models," IZA Discussion Papers 5112, Institute of Labor Economics (IZA).
    32. David Greenaway & Richard Kneller, 2007. "Firm heterogeneity, exporting and foreign direct investment," Economic Journal, Royal Economic Society, vol. 117(517), pages 134-161, February.
    33. repec:ran:wpaper:710-1 is not listed on IDEAS
    34. Casey Ichniowski & Kathryn L. Shaw, 2009. "Insider Econometrics: Empirical Studies of How Management Matters," NBER Working Papers 15618, National Bureau of Economic Research, Inc.
    35. Roger Koenker & Kevin F. Hallock, 2001. "Quantile Regression," Journal of Economic Perspectives, American Economic Association, vol. 15(4), pages 143-156, Fall.
    36. George A. Akerlof, 2007. "The Missing Motivation in Macroeconomics," American Economic Review, American Economic Association, vol. 97(1), pages 5-36, March.
    37. Richard Kneller & Mauro Pisu, 2010. "The returns to exporting: evidence from UK firms," Canadian Journal of Economics/Revue canadienne d'économique, John Wiley & Sons, vol. 43(2), pages 494-519, May.
    38. Mahmut Yasar & Carl H. Nelson & Roderick Rejesus, 2006. "Productivity and Exporting Status of Manufacturing Firms: Evidence from Quantile Regressions," Review of World Economics (Weltwirtschaftliches Archiv), Springer;Institut für Weltwirtschaft (Kiel Institute for the World Economy), vol. 142(4), pages 675-694, December.
    39. Tingvall, Patrik Gustavsson & Ljungwall, Christer, 2012. "Is China different? A meta-analysis of export-led growth," Economics Letters, Elsevier, vol. 115(2), pages 177-179.
    40. Holger Görg & Eric Strobl, 2016. "Multinational Companies And Productivity Spillovers: A Meta-Analysis," World Scientific Book Chapters, in: MULTINATIONAL ENTERPRISES AND HOST COUNTRY DEVELOPMENT Volume 53: World Scientific Studies in International Economics, chapter 8, pages 145-161, World Scientific Publishing Co. Pte. Ltd..
    41. Joachim Wagner, 2003. "Unobserved firm heterogeneity and the size-exports nexus: Evidence from German panel data," Review of World Economics (Weltwirtschaftliches Archiv), Springer;Institut für Weltwirtschaft (Kiel Institute for the World Economy), vol. 139(1), pages 161-172, March.
    42. Maria Caterina Bramati & Christophe Croux, 2007. "Robust estimators for the fixed effects panel data model," Econometrics Journal, Royal Economic Society, vol. 10(3), pages 521-540, November.
    43. Daniel S. Hamermesh, 2000. "The Craft of Labormetrics," ILR Review, Cornell University, ILR School, vol. 53(3), pages 363-380, April.
    44. Gamper-Rabindran, Shanti & Khan, Shakeeb & Timmins, Christopher, 2010. "The impact of piped water provision on infant mortality in Brazil: A quantile panel data approach," Journal of Development Economics, Elsevier, vol. 92(2), pages 188-200, July.
    45. David G. Blanchflower, 2007. "International Patterns of Union Membership," British Journal of Industrial Relations, London School of Economics, vol. 45(1), pages 1-28, March.
    46. Natalia Trofimenko, 2008. "Learning by Exporting: Does It Matter Where One Learns? Evidence from Colombian Manufacturing Firms," Economic Development and Cultural Change, University of Chicago Press, vol. 56(4), pages 871-894, July.
    47. Roger Koenker & Achim Zeileis, 2009. "On reproducible econometric research," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 24(5), pages 833-847.
    48. Maria Abreu & Henri L. F. de Groot & Raymond J. G. M. Florax, 2005. "A Meta‐Analysis of β‐Convergence: the Legendary 2%," Journal of Economic Surveys, Wiley Blackwell, vol. 19(3), pages 389-420, July.
    49. Daniel S. Hamermesh, 2007. "Viewpoint: Replication in economics," Canadian Journal of Economics, Canadian Economics Association, vol. 40(3), pages 715-733, August.
    50. Bruno S. Frey & Reiner Eichenberger & René L. Frey, 2009. "Editorial Ruminations: Publishing Kyklos," Kyklos, Wiley Blackwell, vol. 62(2), pages 151-160, April.
    51. Papke, Leslie E. & Wooldridge, Jeffrey M., 2008. "Panel data methods for fractional response variables with an application to test pass rates," Journal of Econometrics, Elsevier, vol. 145(1-2), pages 121-133, July.
    52. Vincenzo Verardi & Joachim Wagner, 2021. "Productivity Premia for German Manufacturing Firms Exporting to the Euro-area and Beyond: First Evidence from Robust Fixed Effects Estimations," World Scientific Book Chapters, in: Joachim Wagner (ed.), MICROECONOMETRIC STUDIES OF FIRMS’ IMPORTS AND EXPORTS Advanced Methods of Analysis and Evidence from German Enterprises, chapter 7, pages 87-109, World Scientific Publishing Co. Pte. Ltd..
    53. Bruno S. Frey & Reiner Eichenberger & Rene L. Frey, 2009. "Editorial Ruminations: Publishing Kyklos," CREMA Working Paper Series 2009-01, Center for Research in Economics, Management and the Arts (CREMA).
    54. repec:spr:weltar:v:144:y:2008:i:4:p:596-635 is not listed on IDEAS
    55. Helmut Fryges, 2009. "The export-growth relationship: estimating a dose-response function," Applied Economics Letters, Taylor & Francis Journals, vol. 16(18), pages 1855-1859.
    56. Mark Doms & Eric J. Bartelsman, 2000. "Understanding Productivity: Lessons from Longitudinal Microdata," Journal of Economic Literature, American Economic Association, vol. 38(3), pages 569-594, September.
    57. Vincenzo Verardi & Christophe Croux, 2009. "Robust regression in Stata," Stata Journal, StataCorp LP, vol. 9(3), pages 439-453, September.
    58. Sophia Dimelis & Helen Louri, 2002. "Foreign ownership and production efficiency: a quantile regression analysis," Oxford Economic Papers, Oxford University Press, vol. 54(3), pages 449-469, July.
    59. Freeman, Richard B. & Shaw, Kathryn L. (ed.), 2009. "International Differences in the Business Practices and Productivity of Firms," National Bureau of Economic Research Books, University of Chicago Press, number 9780226261942, December.
    60. Schnabel, Claus & Wagner, Joachim, 2005. "Determinants of Union Membership in 18 EU Countries : Evidence from Micro Data, 2002/03," Discussion Papers 31, Friedrich-Alexander University Erlangen-Nuremberg, Chair of Labour and Regional Economics.
    61. Anna Maria Falzoni & Mara Grasseni, 2005. "Home Country Effects of Investing Abroad: Evidence from Quantile Regressions," KITeS Working Papers 170, KITeS, Centre for Knowledge, Internationalization and Technology Studies, Universita' Bocconi, Milano, Italy, revised Jun 2005.
    62. Koenker, Roger W & Bassett, Gilbert, Jr, 1978. "Regression Quantiles," Econometrica, Econometric Society, vol. 46(1), pages 33-50, January.
    63. Marc J. Melitz, 2003. "The Impact of Trade on Intra-Industry Reallocations and Aggregate Industry Productivity," Econometrica, Econometric Society, vol. 71(6), pages 1695-1725, November.
    64. Chen, Songnian & Khan, Shakeeb, 2008. "Semiparametric Estimation Of Nonstationary Censored Panel Data Models With Time Varying Factor Loads," Econometric Theory, Cambridge University Press, vol. 24(5), pages 1149-1173, October.
    65. Papke, Leslie E & Wooldridge, Jeffrey M, 1996. "Econometric Methods for Fractional Response Variables with an Application to 401(K) Plan Participation Rates," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 11(6), pages 619-632, Nov.-Dec..
    66. Laura De Dominicis & Raymond J. G. M. Florax & Henri L. F. De Groot, 2008. "A Meta‐Analysis On The Relationship Between Income Inequality And Economic Growth," Scottish Journal of Political Economy, Scottish Economic Society, vol. 55(5), pages 654-682, November.
    67. Ricardo A. López, 2005. "Trade and Growth: Reconciling the Macroeconomic and Microeconomic Evidence," Journal of Economic Surveys, Wiley Blackwell, vol. 19(4), pages 623-648, September.
    Full references (including those not matched with items on IDEAS)

    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.
    1. David Powell & Joachim Wagner, 2010. "The Exporter Productivity Premium along the Productivity Distribution: First Evidence from a Quantile Regression Approach for Fixed Effects Panel Data Models," Working Paper Series in Economics 182, University of Lüneburg, Institute of Economics.
    2. Joachim Wagner, 2016. "International Trade and Firm Performance: A Survey of Empirical Studies since 2006," World Scientific Book Chapters, in: Microeconometrics of International Trade, chapter 2, pages 43-87, World Scientific Publishing Co. Pte. Ltd..
    3. David Powell & Joachim Wagner, 2021. "The Exporter Productivity Premium Along the Productivity Distribution: Evidence from Quantile Regression with Nonadditive Firm Fixed Effects," World Scientific Book Chapters, in: Joachim Wagner (ed.), MICROECONOMETRIC STUDIES OF FIRMS’ IMPORTS AND EXPORTS Advanced Methods of Analysis and Evidence from German Enterprises, chapter 9, pages 121-149, World Scientific Publishing Co. Pte. Ltd..
    4. Joachim Wagner, 2015. "New Methods for the Analysis of Links between International Firm Activities and Firm Performance: A Practitioner's Guide," The World Economy, Wiley Blackwell, vol. 38(4), pages 704-715, April.
    5. David Powell & Joachim Wagner, 2011. "The Exporter Productivity Premium along the Productivity Distribution Evidence from Unconditional Quantile Regression with Firm Fixed Effects," Working Papers WR-837, RAND Corporation.
    6. Neil Foster-McGregor & Anders Isaksson & Florian Kaulich, 2014. "Importing, exporting and performance in sub-Saharan African manufacturing firms," Review of World Economics (Weltwirtschaftliches Archiv), Springer;Institut für Weltwirtschaft (Kiel Institute for the World Economy), vol. 150(2), pages 309-336, May.
    7. Joachim Wagner, 2014. "Exports, foreign direct investments and productivity: are services firms different?," The Service Industries Journal, Taylor & Francis Journals, vol. 34(1), pages 24-37, January.
    8. Alexander Vogel & Joachim Wagner, 2021. "Robust Estimates of Exporter Productivity Premia in German Business Services Enterprises," World Scientific Book Chapters, in: Joachim Wagner (ed.), MICROECONOMETRIC STUDIES OF FIRMS’ IMPORTS AND EXPORTS Advanced Methods of Analysis and Evidence from German Enterprises, chapter 14, pages 239-263, World Scientific Publishing Co. Pte. Ltd..
    9. Joachim Wagner, 2016. "Exports, Imports and Profitability: First Evidence for Manufacturing Enterprises," World Scientific Book Chapters, in: Microeconometrics of International Trade, chapter 9, pages 311-338, World Scientific Publishing Co. Pte. Ltd..
    10. Neil Foster-McGregor, 2012. "Innovation and Technology Transfer across Countries," wiiw Research Reports 380, The Vienna Institute for International Economic Studies, wiiw.
    11. Joachim Wagner & Yama Temouri, 2021. "Do Outliers and Unobserved Heterogeneity Explain the Exporter Productivity Premium? Evidence from France, Germany and the United Kingdom," World Scientific Book Chapters, in: Joachim Wagner (ed.), MICROECONOMETRIC STUDIES OF FIRMS’ IMPORTS AND EXPORTS Advanced Methods of Analysis and Evidence from German Enterprises, chapter 13, pages 223-236, World Scientific Publishing Co. Pte. Ltd..
    12. Joachim Wagner, 2011. "Productivity and International Firm Activities: What do we know?," Working Paper Series in Economics 194, University of Lüneburg, Institute of Economics.
    13. David Powell & Joachim Wagner, 2011. "The Exporter Productivity Premium along the Productivity Distribution Evidence from Unconditional Quantile Regression with Firm Fixed Effects," Working Papers 837, RAND Corporation.
    14. Alexandre Gazaniol & Frédéric Peltrault & Jean-Marc Siroen, 2010. "Les performances des entreprises françaises implantées à l’étranger," Économie et Statistique, Programme National Persée, vol. 435(1), pages 149-167.
    15. Temouri, Yama & Vogel, Alexander & Wagner, Joachim, 2013. "Self-selection into export markets by business services firms – Evidence from France, Germany and the United Kingdom," Structural Change and Economic Dynamics, Elsevier, vol. 25(C), pages 146-158.
    16. Neil Foster & Roman Stöllinger & Carlo Altomonte & Richard Kneller, 2012. "The Trade-Productivity Nexus in the European Economy," FIW Specials series 005, FIW.
    17. Federici, Daniela & Parisi, Valentino & Ferrante, Francesco, 2020. "Heterogeneous firms, corporate taxes and export behavior: A firm-level investigation for Italy," Economic Modelling, Elsevier, vol. 88(C), pages 98-112.
    18. Neil Foster-McGregor & Anders Isaksson & Florian Kaulich, 2015. "Importing, exporting and the productivity of services firms in Sub-Saharan Africa," The Journal of International Trade & Economic Development, Taylor & Francis Journals, vol. 24(4), pages 499-522, June.
    19. repec:dau:papers:123456789/7408 is not listed on IDEAS
    20. Maria Rosaria Ferrante & Marzia Freo, 2012. "The Total Factor Productivity Gap between Internationalised and Domestic Firms: Net Premium or Heterogeneity Effect?," The World Economy, Wiley Blackwell, vol. 35(9), pages 1186-1214, September.
    21. Vincenzo Verardi & Joachim Wagner, 2021. "Productivity Premia for German Manufacturing Firms Exporting to the Euro-area and Beyond: First Evidence from Robust Fixed Effects Estimations," World Scientific Book Chapters, in: Joachim Wagner (ed.), MICROECONOMETRIC STUDIES OF FIRMS’ IMPORTS AND EXPORTS Advanced Methods of Analysis and Evidence from German Enterprises, chapter 7, pages 87-109, World Scientific Publishing Co. Pte. Ltd..

    More about this item

    Keywords

    international firm activities; heterogeneous firms; stylized facts; robust statistics; replication; meta anaysis;
    All these keywords.

    JEL classification:

    • F14 - International Economics - - Trade - - - Empirical Studies of Trade
    • C21 - Mathematical and Quantitative Methods - - Single Equation Models; Single Variables - - - Cross-Sectional Models; Spatial Models; Treatment Effect Models
    • C23 - Mathematical and Quantitative Methods - - Single Equation Models; Single Variables - - - Models with Panel Data; Spatio-temporal Models

    NEP fields

    This paper has been announced in the following NEP Reports:

    Statistics

    Access and download statistics

    Corrections

    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:iza:izadps:dp5175. 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: Holger Hinte (email available below). General contact details of provider: https://edirc.repec.org/data/izaaade.html .

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service. RePEc uses bibliographic data supplied by the respective publishers.