
- Location
- Burg. Oudlaan 50, Rotterdam
- iverheul@rsm.nl
More information
Profile
Ingrid Verheul is Assistant Professor of Entrepreneurship at the Centre for New Business Venturing and Entrepreneurship at Rotterdam School of Management. She is affiliated with the research institute EIM Business and Policy Research. Her research interests cover different aspects of entrepreneurship. First, she is involved in research on gender differences in entrepreneurship. She wrote her PhD. thesis on this topic, which she defended June 2005 at the Erasmus School of Economics. Several studies have been published in international academic journals including Journal of Business Venturing; Small Business Economics; Entrepreneurship and Regional Development and International Small Business Journal. Second, her research focuses the determinants of entrepreneurship, which becomes visible in the co-editorship of the book: Entrepreneurship: Determinants and Policy in a European-US Comparison published by Kluwer Academic Publishers in 2002. Other research interests include firm entry and exit, entrepreneurship education and enterprise policy. Ingrid Verheul is full member of the Erasmus Research Institute for Management (ERIM). She is ad-hoc reviewer for several international journals including Journal of Business Venturing; Small Business Economics; Entrepreneurship Theory and Practice; International Small Business Journal and Entrepreneurship and Regional Development. She is member of the scientific committee of the Dutch Federation of Female Entrepreneurs (FZN).
- A.B. Wismans, A.R. Thurik, I. Verheul, O. Torrès & K. Kamei (2020). Attention‐Deficit Hyperactivity Disorder Symptoms and Entrepreneurial Orientation: A Replication Note. Applied Psychology, 69 (3), 1093-1112. doi: 10.1111/apps.12247
- D.A. Lerner, I. Verheul & A.R. Thurik (2019). Entrepreneurship and attention deficit/hyperactivity disorder: a large-scale study involving the clinical condition of ADHD. Small Business Economics, 53 (2), 381-392. doi: 10.1007/s11187-018-0061-1
- P.C. Patel, C.A. Rietveld & I. Verheul (2019). Attention deficit hyperactivity disorder (ADHD) and earnings in later-life self-employment. Entrepreneurship Theory and Practice. doi: 10.1177/1042258719888641
- D.A. Lerner, R.A. Hunt & I. Verheul (2018). Dueling Banjos: Harmony and Discord between ADHD and Entrepreneurship. The Academy of Management Perspectives, 32 (2), 266-286. doi: 10.5465/amp.2016.0178
- K.M. Smolka, I. Verheul, K. Burmeister-Lamp & P.P.M.A.R. Heugens (2018). Get it together! Synergistic effects of causal and effectual decision-making logics on venture performance. Entrepreneurship Theory and Practice, 42 (4), 571-604. doi: 10.1111/etap.12266
- A.R. Thurik, A. Khedhaouria, O. Torrès & I. Verheul (2016). ADHD symptoms and entrepreneurial orientation of small firm owners. Applied Psychology, 65 (3), 568-586. doi: 10.1111/apps.12062
- I. Verheul, W.J.R. Rietdijk, J. Block, I.H.A. Franken, H. Larsson & R. Thurik (2016). The association between attention-deficit/hyperactivity (ADHD) symptoms and self-employment. European Journal of Epidemiology, 31 (8), 767-801. doi: 10.1007/s10654-016-0159-1
- P.W. van der Zwan, A.R. Thurik, I. Verheul & J. Hessels (2016). Factors influencing the entrepreneurial engagement of opportunity and necessity entrepreneurs. Eurasian Business Review, 6 (3), 273-295. doi: 10.1007/s40821-016-0065-1
- M.A. Carree, R. Piergiovanni, E. Santarelli & I. Verheul (2015). Factors favoring innovation from a regional perspective: A comparison of patents and trademarks. International Entrepreneurship and Management Journal, 11 (4), 793-810. doi: 10.1007/s11365-014-0313-8
- I. Verheul, J.H. Block, K. Burmeister, A.R. Thurik, H.W. Tiemeier & Roxana Turturea (2015). ADHD-like behavior and entrepreneurial intentions. Small Business Economics, 45 (1), 85-101. doi: 10.1007/s11187-015-9642-4
- P.W. van der Zwan, I. Verheul, A.R. Thurik & I. Grilo (2013). Entrepreneurial progress: climbing the entrepreneurial ladder in Europe and the US. Regional Studies, 47 (5), 803-825. doi: 10.1080/00343404.2011.598504
- N. Bosma, J. Hessels, V. Schutjens, C.M. van Praag & I. Verheul (2012). Entrepreneurship and role models. Journal of Economic Psychology, 33 (2), 410-424. doi: 10.1016/j.joep.2011.03.004
- P.W. van der Zwan, I. Verheul & A.R. Thurik (2012). The entrepreneurial ladder, gender and regional development. Small Business Economics, 39 (3), 627-643. doi: 10.1007/s11187-011-9334-7
- M.A. Carree & I. Verheul (2012). What makes entrepreneurs happy? Determinants of satisfaction among founders. Journal of Happiness Studies, 2012 (13), 371-387. doi: 10.1007/s10902-011-9269-3
- I. Verheul, A.R. Thurik, I. Grilo & P.W. van der Zwan (2012). Explaining preferences and actual involvement in self-employment: new insights into the role of gender. Journal of Economic Psychology, 33 (2), 325-341. doi: 10.1016/j.joep.2011.02.009
- I. Verheul & L. van Mil (2011). What determines the growth ambition of Dutch early-stage entrepreneurs? International Journal of Entrepreneurial Venturing, 3 (2), 183-207. doi: 10.1504/IJEV.2011.039340
- M.A. Carree, I. Verheul & E. Santarelli (2011). Sectoral patterns of firm exit in Italian provinces. Journal of Evolutionary Economics, 21 (3), 499-517. doi: 10.1007/s00191-010-0191-3
- P.W. van der Zwan, I. Verheul & A.R. Thurik (2011). The entrepreneurial ladder in transition and non-transition economies. Entrepreneurship Research Journal, 1 (2):4. doi: 10.2202/2157-5665.1012
- M.A. Carree & I. Verheul (2009). Time allocation by the self-employed: the determinants of the number of working hours in start-ups. Applied Economics Letters, 16 (15), 1511-1515. doi: 10.1080/13504850701580542
- S. Arando, I. Pena & I. Verheul (2009). Market entry of firms with different legal forms: An empirical test of the influence of institutional factors. International Entrepreneurship and Management Journal, 5 (1), 77-95. doi: 10.1007/s11365-008-0094-z
- I. Verheul, M.A. Carree & E. Santarelli (2009). Regional opportunities and policy initiatives for new venture creation. International Small Business Journal, 27 (5), 608-625. doi: 10.1108/dlo.2010.08124dad.007
- E. Santarelli, M.A. Carree & I. Verheul (2009). Unemployment and firm entry and exit: an update on a controversial relationship. Regional Studies, 43 (8), 1061-1073. doi: 10.1080/00343400801968361
- I. Verheul, M.A. Carree & A.R. Thurik (2009). Allocation and productivity of time in new venture of female and male entrepreneurs. Small Business Economics, 33 (3), 273-291. doi: 10.1007/s11187-009-9174-x
- M.A. Carree, E. Santarelli & I. Verheul (2008). Firm entry and exit in Italian provinces and the relationship with unemployment. International Entrepreneurship and Management Journal, 4 (2), 171-186. doi: 10.1007/s11365-007-0060-1
- R. Piergiovanni, M.A. Carree, E. Santarelli & I. Verheul (2007). Politiche per l'imprenditorialita e self-employment, un'analisi territoriale. l'Industria: Rivista di Economia e Politica Industriale, 27 (2), 199-219.
- I. Verheul, A.J. van Stel, A.R. Thurik & D. Urbano (2006). The Relationship between Business Ownership and Unemployment in Spain: A Matter of Quantity or Quality? Estudios de Economia Aplicada, 24 (2), 105-127.
- I. Verheul, A.J. van Stel & A.R. Thurik (2006). Explaining female and male entrepreneurship at the country level. Entrepreneurship and Regional Development, 18 (2), 151-183. doi: 10.1080/08985620500532053
- I. Verheul, L.M. Uhlaner & A.R. Thurik (2005). Business accomplishments, gender and entrepreneurial self-image. Journal of Business Venturing, 20 (4), 483-518. doi: 10.1016/j.jbusvent.2004.03.002
- I.J.M. van der Kuip & I. Verheul (2004). Early development of entrepreneurial qualities: the role of initial education. International Journal of Entrepreneurship Education, 2 (2), 203-226.
- I. Verheul & P.A. Risseeuw (2002). Gender differences in strategy and human resource management: the case of the Dutch real estate brokerage. International Small Business Journal, 20 (4), 439-471.
- I. Verheul & A.R. Thurik (2001). Start-up capital: 'does gender matter'? Small Business Economics, 16 (4), 329-345. doi: 10.1023/A:1011178629240
- A.R. Thurik, A.J. van Stel, I. Verheul & L. Baljeu (2008). Entrepreneurship and unemployment in Japan. Medium Econometrische Toepassingen, 16 (1), 18-23.
- H. Okamuro, A.J. van Stel & I. Verheul (2017). Understanding the drivers of an 'entrepreneurial' economy: Lessons from Japan and the Netherlands. In J. Bonnet, M. Dejardin & D. Garcia Perez de Lema (Eds.), Exploring the Entrepreneurial Society: Institutions, Behavior & Outcomes (pp. 3-21). Cheltenham: Edward Elgar
- I. Verheul & A.J. van Stel (2010). Entrepreneurial diversity and economic growth. In J. Bonnet, D. Garcia & H. van Auken (Eds.), The Entrepreneurial Society: How to Fill the Gap between Knowledge and Innovation (pp. 17-36). Edward Elgar
- M.A. Carree, R. Piergiovanni, E. Santarelli & I. Verheul (2009). Policies fostering new firm formation and self-employment in Italy: An empirical exercise. In J. Leitao & R. Baptista (Eds.), Public Policies for Fostering Entrepreneurship: A European Perspective (International Studies in Entrepreneurship) (pp. 15-34). Dordrecht: Springer doi: 10.1007/978-1-4419-0249-8
- I. Verheul & A.R. Thurik (2006). Start-up capital: does gender matter? In C.G. Brush, N.M. Carter, E.J. Gatewood, P.G. Greene & M.M. Hart (Eds.), Woman and Entrepreneurship: ContemporaryClassics (International Library of Entrepreneurship Series) (pp. 336-352). Cheltenham: Edward Elgar Publishing
- L.M. Uhlaner, E. Dekkers & I. Verheul (2003). Ondernemen in het familiebedrijf. In P.A. Risseeuw & A.R. Thurik (Eds.), Handboek ondernemers en adviseurs: Management en economie in het midden- en kleinbedrijf (pp. 279-300). Deventer: Kluwer Bedrijfsinformatie
- I. Verheul, A.R.M. Wennekers, D.B. Audretsch & A.R. Thurik (2003). An eclectic theory of entrepreneurship: policies institution and culture. In D.B. Audretsch (Ed.), SMEs in the age of globalization (pp. 536-606). Cheltenham: Edward Elgar Publishing
- A.R. Thurik & I. Verheul (2003). The relationship between entrepreneurship and unemployment: the case of Spain. In E. Genescâ, D. Urbano, J. Capelleras, C. Guallarte & J. Vergès (Eds.), Creatión de empresas - entrepreneurship (pp. 521-547). Barcelona: Servei de Publicacions de la UAB
- E. Stigter & I. Verheul (2003). Vrouwelijk ondernemerschap. In P.A. Risseeuw & A.R. Thurik (Eds.), Handboek ondernemers en adviseurs: management en economie van het midden- en kleinbedrijf (2nd edition) (pp. 185-206). Deventer: Kluwer Bedrijfsinformatie
- C.M. Henriquez, I. Verheul, I. van der Geest & I. Bisschof (2002). Determinants of entrepreneurship in France. In D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wennekers (Eds.), Entrepreneurship: determinants and policy in a European-US comparison (pp. 83-120). Boston/Dordrecht: Kluwer Academic Publishers
- I. Verheul, N. Bosma, M. van Ginkel, D. Longerbone & R. Prins (2002). Determinants of entrepreneurship in the Netherlands. In D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wennekers (Eds.), Entrepreneurship: Determinants and policy in a European-US comparison (pp. 121-162). Boston/Dordrecht: Kluwer
- D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wennekers (2002). Understanding entrepreneurship across countries and over time. In D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wennekers (Eds.), Entrepreneurship: determinants and policy European-US comparison (Economics of Science, Technology and Innovation, Volume 27) (pp. 1-10). Boston/Dodrecht/London: Kluwer Academic Publishers
- I. Verheul, S. Schüller & J. van Spronsen (2002). Determinants of entrepreneurship in Germany. In D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wnnekers (Eds.), Entrepreneurship: Determinants and policy in a European-US comparison (pp. 163-207). Boston/Dordrecht: Kluwer Academic Publishers
- I. Verheul, N. Bosma, F. van der Nol & T. Wong (2002). Determinants of entrepreneurship in USA. In D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wennekers (Eds.), Determinants and policy in a European-US comparison (pp. 209-245). Boston/Dordrecht: Kluwer Academic Publishers
- I. Verheul, A.R.M. Wennekers, D.B. Audretsch & A.R. Thurik (2002). An eclectic theory of entrepreneurship: policies institutions and culture. In D.B. Audretsch, A.R. Thurik, I. Verheul & S. Wennekers (Eds.), Entrepreneurship: determinants and policy in a European-US comparison (pp. 11-81). Boston/Dordrecht: Kluwer Academic Publishers
- D.B. Audretsch, A.R. Thurik, I. Verheul & A.R.M. Wennekers (Ed.). (2002). Entrepreneurship: Determinants and Policy in a European-US Comparison. Boston/Dordrecht: Kluwer Academic Publishers
- I. Verheul, A.R. Thurik, J. Hessels & P.W. van der Zwan (2010). Factors influencing the entrepreneurial engagement of opportunity and necessity entrepreneurs. (Research Reports, no H201011). Zoetermeer: EIM
- I. Verheul, A.R. Thurik & I. Grilo (2008). Explaining preferences and actual involvement in self-employment: New insights into the role of gender. (Extern rapport, Scales paper, no H200803). Zoetermeer: EIM Business and Policy Research
- I. Verheul & L. Mil, van (2008). What determines the growth ambition of Dutch early-stage entrepreneurs? (Extern rapport, Scales paper, no H200811). Zoetermeer: EIM Business and Policy Research
- I. Verheul & M.A. Carree (2008). Overoptimism among founders: The role of information and motivation. (Intern rapport, ERIM Research in Management, no ERS-2008-008-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul, A.R. Thurik & I. Grilo (2008). Explaining preferences and actual involvement in self-employment: New insights into the role of gender. (Intern rapport, Research in Management, no ERS-2008-003-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul, M.A. Carree & E. Santarelli (2007). Regional opportunities and policy initiatives for new venture creation. (Intern rapport, ERIM Research in Management, no ERS-2007-092-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul, M.A. Carree & A.R. Thurik (2007). Allocation and productivity of time in new ventures of female and male entrepreneurs. (Intern rapport, Research in Management, no 2007-009-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul & A.J. van Stel (2007). Entrepreneurial diversity and economic growth. (Intern rapport, ERIM Research in Management, no ERS-2007-070-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul, A.J. van Stel, A.R. Thurik & L. Baljeu (2007). The relationship between entrepreneurship and unemployment in Japan. (Intern rapport, Discussion Papers, no TI2007-080/3). 3000 DR Rotterdam: TINBERGEN INSTITUUT
- I. Verheul (2007). Commitment or control? Human Resource Management Practices in Female and Male-Led Businesses. (Intern rapport, ERIM Research in Management, no ERS-2007-071-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul & A.J. van Stel (2007). Entrepreneurial diversity and economic growth. (Extern rapport, Scales paper, no H200701). Zoetermeer: EIM Business and Policy Research
- I. Verheul & M.A. Carree (2007). Overoptimism among entrepreneurs in new ventures: the role of information and motivation. (Extern rapport, Scales paper, no H200723). Zoetermeer: EIM Business and Policy Research
- I. Grilo, A.R. Thurik, I. Verheul & P.W. van der Zwan (2007). Climbing the entrepreneurial ladder: The role of gender. (Intern rapport, ERIM Research in Management, no ERS-2007-098-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul, M.A. Carree & A.R. Thurik (2006). Allocation and productivity of time in new ventures of female and male entrepreneurs. (Extern rapport, Papers on Entrepreneurship, Growth and Public Policy, no #01-2006). Jena, Germany: Max Planck Institute of Economics
- I. Verheul, A.J. van Stel & A.R. Thurik (2006). Explaining female and male entrepreneurship at the country level. (Extern rapport, Scales paper, no N200510 (early version: N200403)). Zoetermeer: EIM Business and Policy Research
- I. Verheul, A.R. Thurik & I. Grilo (2006). Determinants of self-employment preference and realization among women and men in Europe and the United States. (Scales paper, no H200622 (early version: N200513)). Zoetermeer: EIM Business and Policy Research
- A.J. van Stel, A.R. Thurik, I. Verheul & L. Baljeu (2006). The contribution of business ownership in bringing down unemployment in Japan. (Extern rapport, Papers on Entrepreneurship, Growth and Public Policy, no #05-2006). Jena, Germany: Max Planck Institute of Economics
- R.R. Bhola, I. Verheul, A.R. Thurik & I. Grilo (2006). Explaining engagement levels of opportunity and necessity entrepreneurs. (Scales paper, no H200610). Zoetermeer: EIM Business and Policy Research
- I. Verheul, A.J. van Stel & A.R. Thurik (2005). Explaining Female and Male Entrepreneurship at the Country Level. (Intern rapport, ERIM Research in Management, no ERS-2005-089-ORG). 3000 DR Rotterdam: ERIM
- I. Verheul, A.J. van Stel & A.R. Thurik (2005). Explaining female and male entrepreneurship at the country level. (Extern rapport, Papers on Entrepreneurship, Growth and Public Policy, no #34-2005). Jena, Germany: Max Planck Institute of Economics
- I. Verheul, L.M. Uhlaner & A.R. Thurik (2004). Business accomplishments, gender and entrepreneurial self-image. (Extern rapport, Discussion Paper, no 10-2004). Jena, Germany: Max Planck Institute of Economics
- I. Verheul, A.J. van Stel & A.R. Thurik (2004). Explaining female and male entrepreneurship across 29 countries. (Extern rapport, Scales Reports, no N200403). Zoetermeer: EIM Business and Policy Research
- J. van Acht, J. Stam, A.R. Thurik & I. Verheul (2004). Business ownership and unemployment in Japan. (Intern rapport, Discussion Papers, no TI04-036/3). 3000 DR Rotterdam: TINBERGEN INSTITUUT
- M.A. Carree & I. Verheul (2004). Time allocation by the self-employed: the determinants of the number of working hours in start-ups. (Extern rapport, Memorandum, no RM/04/022). Maastricht: METEOR Research
- I. Verheul, A.J. van Stel & A.R. Thurik (2004). Explaining female and male entrepreneurship across 29 countries. (Extern rapport, Papers on Entrepreneurship, Growth and Public Policy, no #08-2004). Jena, Germany: Max Planck Institute of Economics
- J. van Acht, J. Stam, A.R. Thurik & I. Verheul (2004). Business ownership and unemployment in Japan. (Extern rapport, Papers on Entrepreneurship, Growth and Public Policy, no #09-2004). Jena, Germany: Max Planck Institute of Economics
- I. Verheul, M.A. Carree & A.R. Thurik (2004). Allocation and productivity of time in new ventures of female and male entrepreneurs. (Extern rapport, Scales paper, no N200411). Zoetermeer: EIM Business and Policy Research
- I. Verheul (2004). Commitment or control? Human resource management in female- and male-led business. (Extern rapport, SCALES paper, no N200402 (early version: N200306)). Zoetermeer: EIM Business and Policy Research
- I. Verheul & A.R. Thurik (2003). Explaining the entrepreneurial activity rate of women: a macro-level perspective. (Extern rapport, Scales Paper, no N200304). Zoetermeer: EIM Business and Policy Research
- I. Verheul, L.M. Uhlaner & A.R. Thurik (2003). Business accomplishments, gender and entrepreneurial self-image. (Extern rapport, Scales Reports, no N200312). Zoetermeer: EIM Business and Policy Research
- I. Verheul, L.M. Uhlaner & A.R. Thurik (2002). Entrepreneurial activity, self-perception and gender. (Intern rapport, ERIM Research in Management, no ERS-2002-03-STR). 3000 DR Rotterdam: ERIM
- I. Verheul, A.R.M. Wennekers, D.B. Audretsch & A.R. Thurik (2001). An eclectic theory of entrepreneurship: policies, institutions and culture. (Intern rapport, Discussion Paper Tinbergen Institute, no 01-030/3). 3000 DR Rotterdam: TINBERGEN INSTITUUT
- I. Verheul, A.R.M. Wennekers, D.B. Audretsch & A.R. Thurik (2001). An eclectic theory of entrepreneurship: policies, institutions and culture. (Extern rapport, Research Report, no H0012). Zoetermeer: EIM
- I. Verheul & A.R. Thurik (2000). Start-up capital: Differences between male and female entrepreneurs. Does gender matter? (Intern rapport, ERIM Research in Management, no ERS-2000-07-STR). 3000 DR Rotterdam: ERIM
- I. Verheul & A.R. Thurik (1999). Start-up capital: differences between male and female entrepreneurs, 'does gender matter?'. (Extern rapport, Research Reports, no H199910). Zoetermeer: EIM Business and Policy Research
- J. Bal, A. Bruins, J. Jonge, de, S. Tan, A.R.M. Wennekers, I. Verheul & A. E. (2007). Ondernemerschap in het primair en voortgezet onderwijs. (Extern rapport, EIM Report, no A200709). Zoetermeer: EIM Business and Policy Research
- I. Kuip, van der & I. Verheul (2003). Early development of entrepreneurial qualities: The role of initial education. (Extern rapport, Scales paper, no N200311). Zoetermeer: EIM Business and Policy Research
- I. Verheul & H.W. Stigter (1999). Financiering van startende vrouwelijke ondernemers. (Extern rapport, EIM Report, no A9916). Zoetermeer: EIM Business and Policy Research
- A.J. van Stel, A.R. Thurik, I. Verheul & L. Baljeu (2006). The relation between entrepreneurship and unemployment in Japan. (Extern rapport, Discussion Paper, no 05-2006). Jena, Germany: Max Planck Institute Of Economics
- I. Verheul, L.M. Uhlaner & A.R. Thurik (2001). Entrepreneurial activity, self-perception and gender. In Conference Proceedings 1, RENT XV, Research in Entrepreneurship and Small Business (pp. 405-423)
- Hans Bruining, I. Verheul & Roxana Turturea (2012). Does it pay to be cheap? How financial bootstrapping affects the performance of new ventures. In Andrew prof Zacharakis (Ed.), Frontiers of Entrepreneurship Research Vol. 32. Frontiers of Entrepreneurship Research 2004 (pp. 14-14). Boston (US): The Arthur M. Blank Center for Entrepreneurship
- I. Verheul (2005, juni 2). Is There a (Fe)male approach? Understanding Gender Differences in Entrepreneurship. Erasmus University Rotterdam (253 pag.) (Rotterdam: Erasmus Research Institute of Management (PhD Serie 054)) Prom./coprom.: prof.dr. A.R. Thurik.
IM Research clinic
- Title
- IM Research clinic
- Year
- 2020
- Year level
- master
IM Research clinic
- Title
- IM Research clinic
- Year
- 2020
- Year level
- master
Behavioral Strategy
- Title
- Behavioral Strategy
- Year
- 2020
- Year level
- PhD, master
Entrepreneurship
- Title
- Entrepreneurship
- Year
- 2020
- Year level
- bachelor 3, bachelor, bachelor 3
Associate Professor
- University
- Erasmus University Rotterdam
- School
- RSM - Rotterdam School of Management
- Department
- Department of Strategic Management and Entrepreneurship