Mplus Users Guide v6.. - Muthén & Muthén

PREFACEWe started to develop Mplus fifteen years ago with the goal of providing researchers withpowerful new statistical modeling techniques. We saw a wide gap between newstatistical methods presented in the statistical literature and the statistical methods usedby researchers in substantively-oriented papers. Our goal was to help bridge this gapwith easy-to-use but powerful software. Version 1 of Mplus was released in November1998; Version 2 was released in February 2001; Version 3 was released in March 2004;Version 4 was released in February 2006; and Version 5 was released in November 2007.We are now proud to present the new and unique features of Version 6. With Version 6,we have gone a considerable way toward accomplishing our goal, and we plan tocontinue to pursue it in the future.The new features that have been added between Version 5 and Version 6 would neverhave been accomplished without two very important team members, TihomirAsparouhov and Thuy Nguyen. It may be hard to believe that the Mplus team has onlytwo programmers, but these two programmers are extraordinary. Tihomir has developedand programmed sophisticated statistical algorithms to make the new modeling possible.Without his ingenuity, they would not exist. His deep insights into complex modelingissues and statistical theory are invaluable. Thuy has developed the post-processinggraphics module and the Mplus editor and language generator. In addition, Thuy hasprogrammed the Mplus language and is responsible for keeping control of the entire codewhich has grown enormously. Her unwavering consistency, logic, and steady and calmapproach to problems keep everyone on target. We feel fortunate to work with such atalented team. Not only are they extremely bright, but they are also hard-working, loyal,and always striving for excellence. Mplus Version 6 would not have been possiblewithout them.Another important team member is Michelle Conn. Michelle was with us at thebeginning when she was instrumental in setting up the Mplus office and has beenmanaging the office for the past six years. In addition, Michelle is responsible forcreating the pictures of the models in the example chapters of the Mplus User’s Guide.She has patiently and quickly changed them time and time again as we have repeatedlychanged our minds. She is also responsible for keeping the website updated andinteracting with customers. Her calm under pressure is much appreciated. JeanManinger joined the Mplus team after Version 4 was released. Jean works with Michelleand has proved to be a valuable team member.