Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without written permission of the author. Alle rechten voorbehouden. Niets uit deze uitgave mag worden verveelvoudigd, in enige vorm of op enige wijze, zonder voorafgaande schriftelijke toestemming van
"Language is a process of free creation; its laws and principles are fixed, but the manner in which the principles of generation are used is free and infinitely varied. Even the interpretation and use of words involves a process of free creation." -Noam Chomsky
AcknowledgementsThis thesis is the result of almost five enjoyable years spent in the department of Research Methodology, Measurement, and Data Analysis (OMD) at the University of Twente. I am deeply appreciative of the many individuals who have supported my work and continually encouraged me through the writing of this dissertation. Without their time, attention, encouragement, thoughtful feedback, and patience, I would not have been able to see it through. Above all, I would like to thank my promoters. Cees Glas, I have learned a great deal from his unique perspective on research, his sharp insight on almost any issue, and his personal integrity and expectations of excellence. I am amazed at his knowledge of mathematical statistics and enthusiasm of psychometrics. Theo de Vries, I am grateful for his inspirational and timely advice and constant encouragement over the last several years. He has been a great advisor for me outside of the academic world as well.I am very fortunate to have had Bernard Veldkamp as my daily supervisor. He has always been ready with brilliant ideas, honest advice and encouraging words whenever I needed them. I enjoy working with him on the novel text mining techniques and all other areas. He has always been patient when explaining the nuances of English words in writing, and has shared with me many witty jokes, metaphors, and lessons on how to strive for work-life balance. I am looking forward to working with him more in the future.I would also like to thank the other members of my graduation committee, Prof. dr. K. Schreurs, Prof. dr. M. Ijzerman, Prof. dr. H. J. van den Herik, Prof. dr. R. Meijer, Dr. E. Vermetten, and Prof. dr. P. A. M. Vierhout, for taking the time to read my thesis.I am very grateful to Maaike van Groen, my first Dutch classmate and friend, and Hanneke Geerlings, my excellent roommate for the last year, for assisting me during the defense as paranymphs.I am indebted to other (former) members in the OMD: Stephanie van den Berg for guiding me to use Winbugs and forcing me to keep practice of the Dutch language; Jean-Paul Fox for teaching me hierarchical IRT models and multilevel linear regressions; Hans Vos and Wim Tielen for giving me opportunities to assist teaching in the pre-master and master courses related to IRT and data analysis; Theo Eggen for teaching me a broad range of resea...