# What does the item response theory measure?

## What does the item response theory measure?

The item response theory (IRT), also known as the latent response theory refers to a family of mathematical models that attempt to explain the relationship between latent traits (unobservable characteristic or attribute) and their manifestations (i.e. observed outcomes, responses or performance).

What are the assumptions of item response theory?

Several key assumptions underlie the IRT framework, including (i) unidimensionality of the measured trait, (ii) local independence, (iii) monotonicity, and (iv) item invariance. Unidimensionality assumes that a set of items on a scale measure just one thing in common.

### What is the difference between classical test theory and item response theory?

The most important difference between CTT and IRT is that in CTT, one uses a common estimate of the measurement precision that is assumed to be equal for all individuals irrespective of their attribute levels. In IRT, however, the measurement precision depends on the latent-attribute value.

What is classical response theory?

Classical Test Theory. Classical test theory is regarded as the “true score theory.” The theory starts from the assumption that systematic effects between responses of examinees are due only to variation in ability of interest.

## What is item analysis and how it can be done?

Item analysis is a process which examines student responses to individual test items (questions) in order to assess the quality of those items and of the test as a whole. The first part assesses the items which made up the exam. The second part shows statistics summarizing the performance of the test as a whole.

What are the disadvantages of item response theory?

Some disadvantages of IRT are strict assumptions, large sample size (minimum 200; 1000 for complex models), more difficult to use than CTT: computer programs not readily available and models are complex and difficult to understand.

### How do you conduct an item response theory?

Although not exhaustive, the general steps involved in an IRT analysis include (1) clarifying the purpose of a study, (2) considering relevant models, (3) conducting a preliminary data inspection, (4) evaluating model assumptions and testing competing models, and (5) evaluating and interpreting results.

What is the advantage of item response theory?

Benefits of IRT include comprehensive analyses and reduction of measurement error, creation of computer adaptive tests, meaningful scaling of latent variables, objective calibration and equating, evaluation of test and item bias, greater accuracy in the assessment of change due to therapeutic intervention, and …

## What are the advantages of item response theory over classical test theory?

The use of IRT with test development has several advantages over CTT mainly because IRT produces person parameter invariance (test scores are not dependent on the particular choice of test items) when model fit is present, and test information functions provide the amount of information or “measurement precision” …

What is item response theory in educational assessment?

Item response theory provides a useful and theoretically well-founded framework for educational measurement. It supports such activities as the construction of measurement instruments, linking and equating measurements, and evaluation of test bias and differential item functioning.

### What is classical item analysis?

Item analysis is, as the name suggests, the evaluation of an individual item in the context of a test. However, item analysis is an important part of test construction in classical test theory because it guides decisions regarding whether to discard, rewrite, or reassign a particular item to another scale.