Item response theory

Item response theory, deals with the study of one particular item. It is method of measuring analysis, test scores, analysis questionnaires, attitudes, and other factors. This theory gives a probability of the person answering the question in a correct manner. Based on the response of the person the nature and character of a person is determined.

Three important fundamentals of Item response theory include:

• Item response functions
• Information functions
• Invariance

Item response theories are broadly classified into two broad categories:

• Unidimensional :  these Unidimensional requires a single dimension or ability.
• Multidimensional: in this Multidimensional, data is hypothesized using multiple traits of abilities.

The benefits of using Item response theories are:

• Item response theory makes stronger assumptions and also provides stronger conclusions
• Item response theory’s model-based nature is more advantageous then classical test theory findings
• Item response theory gives more improvements in scaling people and items.
• Item response theory gives greater flexibility in situations when different samples are being used. In short item response theory is not based on the sample of study.
• Item parameters include difficulty, discrimination, and pseudo guessing.
• Item response theory  can improve the perception and validity of psychological among a wide variety of subject
• Item response theory gives more explicit hypotheses when compared to traditional methods.
• Using Item response theory be can get an nearly accurate answer because Item response theory allows the probability of random error to vary.

Item response theory uses different parameters for measurement. Basically there are three types based on the parameters they use

• 1 PL: this one parameter model makes an assumption that the items in the sample have equal discrimination, so there is minimal guessing involved.
• 2 PL:  this two parameter model makes the assumption that there is minimum guessing involved but the object may vary in location and discrimination.
• 3 PL: this three parameter model can be used in scenarios where guessing the correct answer is highly unlikely.  Like for instances when you have to judge the attitude of a person. Then this model comes in handy.

Questions:

• How accurate is the answer provided by Item response theory?
• How is Item response theory different from the previous models used?