The Item Response Theory framework encompasses a wide range of psychometric methods and mathematical models (latent trait models) to study individual responses to items defining a measurement instrument (multi-item scales such as questionnaires or tests) that is used to assess a specific construct ...

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Meaning of large values of parameter b (|b| >>) 4 in IRT theory

I'm working with a set of data from a 100 itens, 5 alternatives, medicine test and analyzing them by means of IRT (. The IRT - 3 parameter model yielded some values of b that are very large (...
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25 views

how do you estimate irt parameters if Theta and response is given?

I have good Theta estimates for people (from an already existing test). These people have also answered a few (2-5) untried experimental items. How can I get the a,b params for these new items given ...
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76 views

How to interpret meaning of regressors in this logistic regression model?

I'm trying to understand the model in this paper where they treat the item response theory model as a form of logistic regression. In the model the probability of getting an item (question) correct ...
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16 views

Can the test information function be used for a field test item bank?

I am field testing a few forms of items (with embedded anchor items) and will be analyzing the items using IRT, a 2PL model. These items will likely be used to create an item bank that can then create ...
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45 views

MCMC Estimation of Multidimensional 2PL IRT Model Using JAGS

I'm trying to prepare for some more advanced work involving MIRT models I'll be doing later this year by fitting a very simple multidimensional 2PL model to some simulated data using MCMC methods in ...
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32 views

Raschmodel on the single dimension as modeltest for mirt?

For unidimensional dichotomous IRT-Models testing the Rasch Model is a necessary requirement. What about applying multdimensional IRT-Models? Are there any other informationscources except AIC and ...
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26 views

Internal consistency and other item analyses

Is it appropriate to run internal consistency and other item analyses on a test that has questions with different response formats. To be clearer, all questions have a likert response, but some are 5 ...
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42 views

BIC in Item Response Theory Models: Using log(N) vs log(N*I) as a weight

In IRT software packages and in the literature it is common to calculate the BIC as $$ \mathrm{BIC} = -2 \cdot \mathrm{logLik} + \log(N)\mathrm{Npars} $$ where $N$ is the number of rows in wide ...
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42 views

Questions regarding interpretation of item parameters: inconsistent results between classical item analysis and item response analysis

I was not trained as a psychometrician, so my questions may be concept-related. If you know different resources, books, or articles that can clear my confusions, please let me know. Thank you very ...
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62 views

Is it possible to do IRT distractor analysis using R?

I've been using the mirt package to analyse a few response matrixes I have through IRT. However, every time I need to perform distractor analysis, I end up having ...
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135 views

Questions Regarding Item Response Models – the 3PL model vs. the mixture of 2PL and 3PL model

I currently work on an item analysis for an assessment. The assessment consists of 25 multiple-choice questions. Each question has 4 choices with one correct answer. I used different IRT models to ...
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76 views

Item discrimination of poorly targeted items

In test theory, it appears to be widely recognized that very "easy" or "very difficult" items, relative to the ability of the sample of respondents, will have deflated correlations with the rest of ...
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How to calculate the parameter value for a test with Item Response Theory?

Given a set of responses to a test with multiple choice I wish to analyse it with Item Response Theory: wikipedia on IRT. I am planing to use the 3PL (3 parameters) in the Item response function. How ...
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25 views

Is a representative sample necessary to assess construct validity?

To generalize results to a greater population, a representative sample is necessary. In developing a psychometrically valid instrument, via confirmatory factor analysis or item response theory, we are ...
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1answer
130 views

Misfitting of drift rate in Wiener model

In a binary-decision experiment, the accuracy and response time of some subjects were recorded. My goal is to fit a Wiener model to response time and accuracy data. The binary experiment has three ...
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17 views

Extracting latent factor from ranking data

I want to construct a model to link between a set of quantitative engineering parameters (e.g. Sm, Ra) of 9 material samples to a set subjective qualitative rankings of 6 perceived attributes, e.g. ...
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34 views

Recode Binary to scale Variables

I'm looking to find information to recode a set of dichotomous response variables to preferable a 1-5 scale. I have several response variables which when combined with PCA clearly depict certain ...
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1answer
190 views

What is the statistic to calculate Cronbach's alpha for Polytomous items in R

Does anyone know, what is the function which can calculate Cronbach's alpha for polytomous items with different categories in R? Thank you
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83 views

Itemfit to IRT model with missing data

I have matrix of dichotomus correct/false answers with many random missing data. (The data comes from an ability test where questions were randomly drawn from an item bank.) I am trying to find out ...
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40 views

Cut Score Determination in IRT

Cut score or cut point is a minimum achievement or ability that examinees should get in order to get a 'Pass'. In CTT, MCQ scoring in the form of percent-correct scores are applied. Let say we ...
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22 views

Validity in IRT Style

From my reading, I found that IRT generally provides more sophisticated information. Therefore, in regards of unidimensional 3PL IRT model, how should I report the finding about validity in ...
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30 views

Reading recommendations for psychometric refinement

a research project turned up a large number of survey instruments on a specific topic. There is a great deal of conceptual item overlap in these instruments, but they do differ in some key ways, ...
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1answer
54 views

Comparisons of confirmatory and exploratory model in IRT

I am trying to decide whether a theoretically derived (i.e. confirmatory) IRT model fits the data better than some parsimonious (i.e. exploratory) IRT model. Specifically, I have 14 binary indicators ...
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41 views

Likert scale survey student response independence

We administer a confidence survey (likert scale) comprising of 30 items and have conducted PCA to examine dimensionality, item independence and the like. We also conduct student interviews to assess ...
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439 views

Reliability in IRT Style

Reporting 'reliability' in IRT is more to 'informations' obtained and a bit different from a classical way using such as Cronbach alpha and KR20. Therefore, how to report the test reliability in ...
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27 views

Item Information Distorting Scale

I'm refining a psychometric questionnaire and working to estimate (2PL) IRT parameters for the items in order to score the items. It's a small scale consisting of 5 questions. The MAP and VSS-1 ...
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34 views

As a rule of thumb, difference in amount of administered items: classically scored vs adaptive (irt-based) tests?

I am thinking of developing a new adaptive test. One of the main goals is to shorten existing, classically scored tests. Is there a rule of thumb about how many items are needed to administered ...
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60 views

Understanding and applying Item Response Theory

In the process of designing a quiz application that can assess the student for understanding of a particular concept, I came across Item Response Theory. I have absolutely no clue whether applying ...
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52 views

Are there local maxima in the standard 2-pl model or is there proof that there aren't?

I'm looking to use iterative logistic regression to find the parameter values of the 2 pl model: $ P = \sigma(\alpha_{i} (\theta_{s} - \beta_{i})) $ where $ \sigma(x) = \frac{1}{1+e^{-x}} $ I know ...
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100 views

Latent Class Analysis vs Rasch Analysis

I was wondering if anybody could explain the core, philosophical/conceptual differences between Latent Class Analysis and Rasch Analysis. I'm not necessarily referring to the exact mathematical ...
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1answer
37 views

The probability of a student getting a given question correct and the associated uncertainty (Item response theory)

I'm doing some statistics on multiple choice test scores (with item response theory, (http://en.wikipedia.org/wiki/Item_response_theory). I want to know the probability that a student with a certain ...
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469 views

Item Response Theory vs Confirmatory Factor Analysis

I was wondering what the core, meaningful differences are between Item Response Theory and Confirmatory Factor Analysis. I understand that there are differences in the calculations (focusing more on ...
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188 views

How to fit Graded Response Model with lme4::glmer

Thanks to Rijmen et al.(2003), we can fit GRM to the data with lme4::glmer. I think Rasch model is straightforward, with ...
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117 views

Longitudinal data format in WinBUGS or OpenBUGS, different number of items per time point

I am working with longitudinal data, where there are a different number of "items" per time point. I am working with the MCMCdynamicIRT1d function in ...
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171 views

Interpreting discrimination values in IRT polytomous (grm) models. Are there any cut-offs or anchors?

I am working on a project that is looking at the discriminative properties of 6, 5-point Likert items in a scale. I am using the ltm package in R to examine this within a item response theory (irt) ...
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1answer
159 views

How to obtain Item Information Curves for the Partial Credit Model?

I have estimated a Partial Credit Model in Stata following Zheng, X. and Rabe-Hesketh, S. (2007) "Estimating parameters of dichotomous and ordinal item response models using gllamm". I'd like to ...
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111 views

Multigroup Longitudinal Item Response WinBUGS OpenBUGS

I was able to fit the Longitudinal IRT model in Winbugs for an ordinal response by extending the BUGS code I took from the paper by Curtis in JSS http://www.jstatsoft.org/v36/c01/paper/ However, I am ...
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1answer
187 views

Implementing nominal model from Polytomous Item Response Theory

I am attempting to map out the probabilities of observing different categories given different person ability using the Nominal Model. From the handbook of Polymous Item Response Theory 2010, the ...
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1answer
453 views

Longitudinal item response theory models in R

I'm trying to fit longitudinal item response theory (IRT) models in R. I have a test that was administered at multiple measurement occasions. I'd like to examine individuals' growth curves of factor ...
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231 views

Is it possible to fit a Graded Response Model in Stata?

I've been reading about Item Response Theory during the past few weeks and I'd like to use it to examine how my scales are functioning. The response categories are ordinal. If I understood well, the ...
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53 views

Item Response Theory alternatives

What are other approaches than Item Response Theory to model learning of students in standardised tests?
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22 views

Datasets for exploring Cognitive Diagnosis Modelling [closed]

I recently became interested in Cognitive Diagnosis Modelling, which classifies respondents to skill profiles based on their responses and a hypothesized relation between skills and items (Q- or ...
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89 views

BUGS/JAGS for Nominal Response Model

I am a beginner with BUGS/JAGS and I was hoping to gather the opinion of you, experts. I am trying to implement a Nominal Item Response Analysis (Polytomous, not ordered, like a multiple-choice exam) ...
2
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1answer
508 views

How to check goodness of fit for a graded response model in R

I am using the grm function in the ltm package in R. There is no function to check the goodness of fit of the output. How can I ...
2
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1answer
254 views

Mixing dichotomous and polytomous items in one test

I have to evaluate a test paper which contains both dichotomous and polytomous items. I am currently using R. But in R IRT models for scoring of dichotomous and polytomous items are different and I ...
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176 views

Item reliability or fit in IRT-based adaptive tests?

My background is in machine learning and statistics, but I am relatively new to psychometrics and testing. Nearly all of the literature I've found on item reliability refers to Chronbach's alpha or ...
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1answer
84 views

Change in output depending on mirt version

I have a matrix which I'm trying to run through the mirt function of the mirt package: ...
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1answer
44 views

Inferring testlet structure in item response theory

Is it possible to infer the testlet structure in a set of items using item response theory? Specifically, I've created a lot of variations on the story recall task, each variation being scored on 25 ...
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1answer
277 views

How can I handle missing values when fitting IRT model?

I am conducting a study for analyzing male involvement in Family planning. It is of interest to develop an index for the involvement of male. I am currently having difficulties fitting an IRT model ...
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101 views

Calculating the space/distance between scale points (IRT)?

I am working with a seven item Likert Scale (1, 2......6, 7) for a classroom management. How can I calculate the distance between these seven scale points? This is for instrument reliability ...