From a draft of item response theory for psychological research. Despite theoretical differences between item response theory irt and classical test theory ctt, there is a lack of empirical knowledge about how, and to what extent, the irt and cttbased item and person statistics behave differently. Georg rasch 1960 published a book describing several item response models, one of which later became known as the. In addition, irt has had a big impact on psychology by making possible several tools that would be difficult to create without irt. The first is to show how classical test theory ctt can be viewed as a mean and variance i.
Model linear non linear level test item assumption weak i. This article presents health science educators and researchers with an overview of standardized testing in educational measurement. Classical test theory ctt and itemresponse theory irt are testing item assessment approaches. Classical test theory vs item response theory by chris allred. Item response theory is a statistical theory about items, test performance and abilities that are measured by items. Classical test theory item analysis, in measurement theory in action. T or f item response theory has the advantage over classical test theory in that it provides more detailed information regarding each item on a test. Lords book, applications of item response theory to practical testing problems, presented much of the current irt theory in language easily understood by many practitioners. As a result, many of the issues that have arisen in the past 20 years are not treated in the book. Pdf a primer on classical test theory and item response.
Item response theory irt is all about your performance on an exam, and how it relates to individual items or questions on a test. Thus irt models the response of each examinee of a given. Nov 30, 2010 this study compares the psychometric utility of classical test theory ctt and item response theory irt for scale construction with data from higher education student surveys. Item response theory is a general statistical theory about examinee item and test performance and how performance relates to the abilities that are measured by the items in the test. The name item response theory is due to the focus of the theory on the item, as opposed to the testlevel focus of classical test theory. Basics of classical test theory california state university. Part of theinstructional media design commons, and thestatistics and probability commons. Item response theory irt is not only the psychometric theory underlying many major tests today, but it has many important research applications. The history, theoretical frameworks of classical test theory, item response theory irt, and the most common irt models used in modern testing are presented. Item response theory irt is an approach used for survey development, evaluation, and scoring. Educational and psychological measurem june 1998 v58 n3 p357. While the basic concepts of item response theory were, and are, straightforward, the underlying mathematics was.
Chapter 8 the new psychometrics item response theory. A comparative study of classical theory ct and item. Psychometric theory offers two approaches in analyzing test data. However, few studies have empirically examined the. Classical test theory and item response theory the wiley. You design test items to measure various kinds of abilities such as math ability, traits such as. Eric ed466779 classical test theory and item response. While the basic concepts of item response theory were, and are, straightforward, the underlying mathematics was somewhat advanced compared to that of classical test theory. Mar 25, 2010 patientsreported outcomes pro are increasingly used in clinical and epidemiological research. Sage books the ultimate social sciences digital library. An empirical comparison of item response theory and classical test theory spela progar1 and gregor socan2 1mirna pec, slovenija 2university of ljubljana, department of psychology, ljubljana, slovenia abstract. Methodological issues regarding power of classical test. The author shows how ordinal item response theory can be the most efficient method for working with scales with only a few items.
What it is and how you can use the irt procedure to apply it xinming an and yiufai yung, sas institute inc. Summary this chapter presents an overview of classical test theory ctt, strong true. This task connects ctt more closely to irt and provides simplified. Additionally, another limitation of classical test theory is the lack of invariance of the test properties regarding the people you use to determine it. Irt may be regarded as roughly synonymous with latent trait theory. Trait true score observed score classical test theory. Demonstrating the difference between classical test theory. Designed for researchers, psychometric professionals, and advanced students, this book. Breaking free from the limitations of classical test. Computer adaptive testing and differential item functioning. Classical test theory ctt and item response theory irt are widely perceived as representing two very different measurement frameworks.
We propose here that item response theory analyses complements the basic ctt techniques presented in janssen and meier 20. Applying item response theory modeling in educational research. Reliability is seen as a characteristic of the test and of the variance of the trait it measures. This first one today will focus on some of the theory and background of ctt. Compares this method to models for classical test theory. Item response theory provides powerful analytical tools that, even in their most basic applications, can be a valuable. Irt is an example of what psychologists call a latent trait model.
Item responses can be discrete or continuous and can be dichotomous and the item score categories can be ranked or non ranked. It covered basic concepts, comparison to ctt methods, relative efficiency, optimal number of choices per item, flexilevel tests, multistage tests, tailored testing. Classical test theory is an historical predecessor to g theory and, as such, it is sometimes called a parent of g theory. Kline 2005 suggests ctt is known for development of some excellent psychometrically sound. Classical test theory analyses identified 5 of 10 communication items that did not perform well.
However, a new test theory had been developing over the past forty years that was conceptually more powerful than classical test theory. Another branch of psychometric theory is the item response theory irt. In psychometrics, the theory has been superseded by the more sophisticated models in item response theory irt and generalizability theory g theory. Item response theory irt, also known as latent trait theory or modern mental test theory. These three books item response theory principles and applications, item. Based upon items rather than test scores, the new approach was known as item response theory. Using 2008 your first college year yfcy survey data from the cooperative institutional research program at the higher education research institute at ucla, two scales are built and testedone measuring social. Such problems as the lack of invariance of item parameters across examinee groups, and the inadequacy of classical test procedures to detect item bias or to provide a sound basis for measurement in tailored testing, gave rise to a resurgence of interest in item response theory. The theory and practice of item response theory methodology in the social sciences. Classical test theory as a firstorder item response theory.
An ncme instructional module on comparison of classical test. Thus irt models the response of each examinee of a given ability to each item in the test. The theory and practice of item response theory methodology. Sep 09, 2009 this is in sharp contrast to classical test theory, where such an examinee would get a high test score on the easy test and vice versa under item response theory, the examinees ability is fixed and invariant with respect to the items used to measure it. This isnt a big problem on the classical test theory chapters, but more modern chapters such as the item response theory chapter need updating. Item response theory irt vs classical test theory ctt.
Classical test theory ctt and item response theory irt are widely perceived as representing two very differentmeasurement frameworks. Classical test theory assumptions, equations, limitations, and item analyses c lassical test theory ctt has been the foundation for measurement theory for over 80 years. Classical test theory ctt, also known as the true score theory, refers to the analysis of test results based on test scores. Distinguishing differences compare and contrast topics from the lesson, such as classical test theory and item response theory making connections use. Jul 15, 2015 item response theory is a general statistical theory about examinee item and test performance and how performance relates to the abilities that are measured by the items in the test. The item response theory irt, also known as the latent response theory. Demars in her book chapter classical test theory and item response theory still uses axioms based on the basic ctt equation to derive the most common formulas used in. To provide comparisons and a worked example of item and scalelevel evaluations based on three psychometric methods used in patientreported outcome developmentclassical test theory ctt, item response theory irt, and rasch measurement theory rmtin an analysis of the national eye institute visual functioning questionnaire vfq25. Abstract item response theory irt is concerned with accurate test scoring and development of test items.
Developing and measuring information systems scales using item response theory author links open overlay panel thomas rusch a paul benjamin lowry b patrick mair c horst treiblmaier d. Assumptions of item response theory irt in order to resolve these limitations, irt has to make stronger and more restrictive assumptions than ctt. This study compared classical test theory ctt and item response theory irt. This chapter presents an overview of classical test theory ctt, strong true. Item response theory industrialorganizational psychology. Depending on the particular type of measure and the specific circumstances, either one or both approaches should be considered to help maximize the content validity of pro measures.
Two main types of analytical strategies can be found for these data. In psychometrics, item response theory irt is a paradigm for the design, analysis, and scoring of tests, questionnaires, and similar instruments measuring. Comparisons between classical test theory and item. I thought it might be useful to talk about classical test theory ctt and item analysis analytics in a series of blog posts over the next few weeks. There are welldefined theoretical differences between the classical test theory ctt and item response theory irt frameworks. However, whether irt or ctt would be the most appropriate method to analyse pro data remains unknown. Jun 28, 2009 the present report demonstrates the difference between classical test theory ctt and item response theory irt approach using an actual test data for chemistry junior high school students. Comparing classical test theory and item response theory. Item reponses theory ctt testoriented indices like reliability are groupspecific scores are testspecific contribution of item measured using other items e.
Whereas classical test theory focuses on the test as a whole, item response theory shifts its focus to the individual items questions themselves. Classical test theory ctt and item response theory irt ctt and its use in test analysis as the name would imply, classical test theory ctt is one traditional way of understanding test scores. Multiple cateogry item analysis and test scoring using item reponse theory computer. Classical test theory ctt and item response theory irt. Comparisons between classical test theory and item response. Impetus for the development of item response theory as we now. It is understood that in the ctt framework, person and item statistics are test and sampledependent. Using classical test theory, item response theory, and rasch measurement theory to evaluate patientreported outcome measures. True t or f cross cultural fairness in testing has always been a critical factor in the development of tests. In psychometrics, item response theory irt also known as latent trait theory, strong true score theory, or modern mental test theory is a paradigm for the design, analysis, and scoring of tests, questionnaires, and similar instruments measuring abilities, attitudes, or other variables. Classical test theory as a first order item response theory. The example was a 15 item test with a sample size of 600 examinees eighthgrade level.
The theory and practice of item response theory by r. Classical test theory and item response theory analyses of. Using classical test theory, item response theory, and rasch. Based on nonlinear models between the measured latent variable and the item response, item response theory irt enables independent. The conceptual foundations, assumptions, and extensions of the basic premises of ctt have allowed for the development of some excellent psychometrically sound scales. The behavior of the item and person statistics derived from these two measurement frameworks was examined analytically and empirically using a data set obtained from bilog r. These models try to figure if theres an underlying trait that that accounts for your performance on a test.
Item response theory irt is a latent variable modeling approach used to minimize bias and optimize the measurement power of educational and psychological tests and other psychometric applications. May 31, 2015 classical test theory ctt and item response theory irt are testing item assessment approaches. Classical test theory spearman, 1904, novick, 1966focuses on the. An empirical comparison of item response theory and classical. The ctt and irt were compared across two samples and two forms of test on their item difficulty, internal consistency, and measurement errors. Comparison of classical test theory and item response theory. Irt models describe the relationship between a persons response to a survey question and his or her standing on a latent i. Both classical test theory sum scores and item response theory estimates measure the same underlying dimension, but differences in the two scales may lead one to be more preferential than the other in interpreting data. In addition, irt has had a big impact on psychology by making possible. Item response theory has had a significant impact in psychology by allowing for more precise methods of assessing properties of tests compared with classical test theory. Comparisons between classical test theory and item response theory in automated assembly of parallel test forms the journal of technology, learning, and assessment volume 6, number 8 april 2008 a publication of the technology and assessment study collaborative caroline a. The only comparison of both theories that i found was in tenko raykovs book introduction to psychometric theory. Item response theory painted a more promising picture than classical test theory for the 2 communication items that assessed access to an interpreter when needed.
Classical test theory is an influential theory of test scores in the social sciences. Classical test theory vs item response theory by chris. Breaking free from the limitations of classical test theory. Basics of classical test theory theory and assumptions types of reliability example classical test theory classical test theory ctt often called the true score model called classic relative to item response theory irt which is a more modern approach ctt describes a set of psychometric procedures used to test items and scales. The present report demonstrates the difference between classical test theory ctt and item response theory irt approach using an actual test data for chemistry junior high school students. Ordinal item response theory sage publications inc. The new psychometrics item response theory classical test theory is concerned with the reliability of a test and assumes that the items within the test are sampled at random from a domain of relevant items.
Relationships among classical test theory and item response. Applying item response theory modeling in educational research daitrang le iowa state university follow this and additional works at. Educational and psychological measurem june 1998 v58 n3. Important characteristics of both theories are considered in this article, but primary emphasis is placed on g theory. Unfortunately, the few available textbooks are not easily accessible to the audience of psychological researchers and practitioners.
It is based on the application of related mathematical models to testing data. Using classical test theory, item response theory, and. Help students more easily find structure among a subset of data. Item analysis is a hotbutton topic for social conversation okay, maybe just for some people. Item response theory is a newer theory with a focus on test items that adds more tools for solving measurement problems in psychology test bias adaptive testing item selection ctt focuses more on the total score of a scale or subscale. Demars in her book chapter classical test theory and item response theory still uses axioms based on the basic ctt equation to derive the most common formulas used in ctt. The statistics produced under ctt include measures of item difficulty.