Questions tagged [rasch]
The Rasch model is used to model the relation between individual location (ability) on a latent trait and their probability of endorsing a dichotomous item, which is characterized by its difficulty, assuming all items are equally discriminative.
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What is the source of the IRT 1PL discrimination constant?
For a 1PL IRT model you would use the 1.702 constant for the discrimination parameter.
My questions are why, what is the source of this constant?
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Understanding measures of fit for Rasch Model?
I'm trying to learn the details of Rasch modeling and analysis for a psychometric related project. The Rasch model is described as a special case of the generalized linear model, which makes sense ...
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Wright-Map with multiple values for one item
To give some context: I'm quite new to quantitative research in social sciences and learned about IRT, Rasch Reliability and Wright-Maps yesterday.
Today a colleague sent me this image:
and asked ...
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How can I estimate student abilities with a Rasch Model?
I have a dataset of test results. There are 400 students, and 100 items. I ran ltm::rasch in R, and I computed ability scores for each student, and difficulty scores for each item.
I would now like ...
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44 views
Ceiling effect of data-IRT Rasch EFA
Can you do IRT, CFA and/or Rasch if your data has items with large ceiling effects (i.e., no one was choosing the last two options of a 5-point likert scale)? Is it appropriate to do?
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192 views
What is the difference between a Rasch model and a mixed-effects logistic regression?
I've recently been learning about the Rasch model. Previously I've used various kinds of generalized regression, including linear as well as logistic and "vanilla" fixed-effects models as well as ...
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If I know difficulty and thresholds of all items can I build a Rasch model and calculate the ability of new patients
I'm trying to "reverse engineer" a statistal model used in this article: ACTIVLIM : A Rasch-built measure of activity limitations in children and adults with neuromuscular disorders
In this article a ...
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Consequences of violating assumptions about errors in IRT/Rasch based models
In the sorts of measurement models to which one might apply IRT models, including Rasch models, there is not thought to be an error associated with the latent variable. Rather, the latent variable is ...
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Appropriateness of Rasch for formative measurement models
I've spent several months thinking about the issue of whether or not it is appropriate to apply Rasch models to formative measurement models, and I'm looking to see whether anybody else has considered ...
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944 views
What is a design matrix? How do I build a design matrix for Rasch analysis?
I am trying to do an LRSM Rasch analysis of 72-item data. This data has 67 binary items and 5 ternary items. I need to create a "design matrix" in order to analyze this data. I do not really know what ...
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59 views
DIF (differential item functioning) and wanted structural heterogeneous ability of test
I'm calibrating an item pool which enables enables especially to measure different abilitylevels. The item pool is for an economy-achievementest. Therefore, a broad range of items is needed, which ...
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1answer
235 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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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
318 views
Assessing the fit of GLMM implementation of a Rasch model to binary data using lme4
I'd like to assess the fit of the kinds of models described by de Boeck et al (2011) (http://www.jstatsoft.org/v39/i12). They are GLMM implementations of Rasch family models, e.g.:
...
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57 views
Factor analysis in preparation for Rasch
I'm breaking into Rasch modelling and finding it very useful. However I'm just trying to find a way to begin making use of techniques I was familiar with when using classical test methods, such as ...
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1answer
3k views
Is nested ANOVA model appropriate for analysing student performance on a pre/post test?
I am analyzing student performance on a pre/post test designed to assess gains for a week long high school biology curriculum on natural selection.
After comparing pre/post performance using a ...
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1answer
657 views
Classification with 3 groups, repeated measurements, missing values, more predictors than subjects
I am working on a classification problem with the following characteristics:
Individuals belong to one of three groups. The groups are "somewhat ordinal": controls, subclinical and clinical group.
...
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127 views
Dealing with a partially pooled intercept in a Bayesian model
I have a multilevel logistic regression (Rasch), fit in JAGS. Specifically,
$\text{logit} (P(\text{Win})) = \alpha_p + \gamma_w + \delta_{p,w}$
The prior on $\alpha_p$ is partially pooled, $\...
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1answer
166 views
Pros/cons of estimating parameters for missing observations?
Some people are playing a game online. Every time a person plays, a new game board is generated randomly. On generation of a new board, the player can also choose a special weapon. (The choice of ...
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4answers
3k views
Simulating responses to a test for item-response theory
I am developing an online assessment system and I need to calibrate the bank of questions but I do not have enough people to implement a pilot test. That is why I decided to simulate the responses of ...
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3answers
2k views
Is there an R package which implements weighted maximum likelihood for Rasch models?
Is there a package in R which implements the weighted maximum likelihood method (Warm, 1996) for estimating the person parameters in Rasch Models?
