Admission requirements
Master students of Methodology and Statistics
Description
In psychological research, it is often needed to measure latent person characteristics such as mathematics ability, anxiety, and attitude towards political issues. Tests and test scores play an important role. Traditionally, test scores were analyzed by classical test theory, but this has its limitations. Over the last decades, modern test theory has gained influence, since it allows us to analyze the data on the item level and to develop and test a measurement scale of item responses (Item Response Theory models or IRT).
This course offers a theoretical and practical introduction to IRT models. IRT principles are contrasted with CTT principles. Several IRT models are discussed: those for dichotomous item responses (e.g., right/wrong; agree/disagree) and those for categorical responses (e.g., wrong/partially correct/completely correct; multiple choice options). In each of these models, the probability of answering a particular response category is related to the latent characteristic or the latent trait, in a nonlinear way. Several applications of IRT are discussed, including how to calibrate a measurement scale, how to obtain person estimates and how to interpret them, how to find out whether all items ‘work’ the same way for different groups of test takers (differential item functioning), how to compare scores measured on similar but different tests (test equating), and how to make use of computers to make tests shorter (computerized adaptive testing). Several analyses will be practiced in R, with the predefined ltm package.
Course objectives
Students
Acquire knowledge of and insight into the principles of relevant modern test theoretical models and techniques
Acquire knowledge of, insight into, and practical competence w.r.t. analyzing test data with IRT models
Acquire knowledge of and insight in several issues in applications of IRT to different fields of psychology
Timetable
Item Response Theory (2010-2011):
Mode of instruction
Lectures, software demonstrations, and homework assignments.
Assessment method
The final grade for this course will be based on:
Two graded assignments: 1 halfway the course and 1 final assignment.
Written exam
From January 1, 2006 the Faculty of Social Sciences has instituted the Ephorus system to be used by instructors for the systematic detection of plagiarism in students’ written work. Please see the information concerning fraud .
Blackboard
Information on blackboard.leidenuniv.nl
Reading list
Embretson, S. E. & Reise, S. P. (2000). Item Response Theory for Psychologists. Mahwah, NJ: Lawrence Erlbaum Associates, Inc. ISBN10: 0805828192. Approximately €40 – €50.
Rizopoulos, D. (2006). ltm: An R package for latent variable modeling and Item Response Theory analyses. Journal of Statistical Software, 17(5), 1–25. Can be downloaded from <http://www.jstatsoft.org/v17/a05/paper>
Registration
Introduction and enrolment for courses of the first semester will take place on 2 September 2010. Introduction and enrolment for courses of the second semester will take place on 27 January 2011. More information will be available at the website of the Institute of Psychology.
NB: Exam registration will take place via uSis, and will be open between a month and a week before the (re)exam. Students who haven’t registered, cannot participate in the exam.
Contact information
Drs. Marian Hickendorff
Room 3B23
Tel: 071-5273765
E-mail: hickendorff@fsw.leidenuniv.nl