Psychometrics has evolved as a subfield of psychology to become the science of measurement of unobservable individual characteristics.

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180 views

Using Ltm package to calclate 3PL some lines of data seem to go missing

I am hoping someone can help with the following: I have been trying to use the ltm package in R to get person fit estimates using a 3PL model. The problem I have been having is that I start off ...
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0answers
10 views

Correction of data using a correlation

Suppose I have measured the outcome variable A using a (psychophysical) test that determines the ability of a subject to discriminate between two stimuli with a certain difference (the variable X). It ...
4
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1answer
187 views

Omega H asymptotic

In the omega function in the psych package for R, we have several outputs including Hierarchical omega, Asymptotic omega and Total omega. I was reading about the outputs, but I find nothing about ...
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1answer
24 views

An invalid questionnare with valid resultant scores?

In what situation, a questionnaire could be invalid but its resultant scores could be valid? I received a comment from a journal article reviewer that says: In keeping with the preferred ...
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0answers
7 views

Is there any research that compares Likert scale questions to “satisfaction” scale questions?

I'm trying to put together a questionnaire for measuring employee satisfaction with an internal process. I'd like to figure out if there is reason to prefer: ...
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3answers
2k views

A multitrait-multimethod matrix and data set

I am working my way through Multitrait-Multimethod Matrix in a psychometrics class. We're only required to be able to analyze them but I'd really like to be able to construct them. I think I am able ...
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0answers
14 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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2answers
129 views

What is a good method to identify outliers in exam data?

I give my students an exam that has 8 questions on it. Each question is about a particular topic. The exam is made up on the fly by randomly selecting 1 question for each topic from a pool of ...
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1answer
150 views

Validation of a questionnaire in a new population

I have 400 responses to a 20 item questionnaire which purports to measure an attitudinal constuct in medical students. The instrument was validated in the US for a single year of medical students and ...
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0answers
26 views

How to build a perceptual scale using ratio measurements?

I have several physical samples of a material that vary according to some physical measure, e.g. hardness, roughness, brightness etc. Let's use brightness as the example. Now, I am not so much ...
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6answers
1k views

Introduction to structural equation modeling

I am asked by colleagues some help in this subject, that I don’t really know. They made hypotheses on the role of some latent variables in one study, and a referee asked them to formalize this in SEM. ...
3
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0answers
33 views

How high is too high with Cronbach's alpha?

Someone in my organization just sent me a scale they developed (modified items from five separate scales used in published research) to measure an employee's readiness for change. They tested the ...
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1answer
39 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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1answer
226 views

How to apply published factor analysis loadings to sample data to compute factor scores?

I have data on 18 participants responding to a 30-item instrument. I also have a paper in which the researchers performed a principal axis factor analysis on the same survey where they report the item ...
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3answers
1k 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?
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1answer
26 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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0answers
28 views

Confidence interval for psychometric binomial GLM model on more than one subject in R

I'm trying to estimate the confidence interval of a psychometric curve (binomial probit GLM), for a population (now only two subjects). Suppose I've subject "a" and subject "b", which performs ...
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1answer
237 views

How to select next item in polytomous CAT / MIRT?

To make a Computerized Adaptive Test out of a sample of 20 dichotomous items a typical course of action would be to: 1) calibrate respondent data with a R package like mirt or ltm using Rasch, 2PL ...
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2answers
1k views

Error message from grm() in ltm: subscript out of bounds

I am analyzing a survey data set. One of the items in the survey is: ...
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1answer
51 views

Sum of percentile rank scores of two or more variables

I need to sum some variables that are on different scales to make a new one. I'm wondering If it's correct to calculate the percentile scores first, and then to sum them up. Imagine I have to ...
7
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2answers
140 views

A person repeatedly selects the two most similar items out of three. How to model/estimate a perceptual distance between the items?

A person is given three items, say pictures of faces, and is asked to pick out which two of the three faces are the most similar. This is repeated a large number of times with different combinations ...
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0answers
22 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 ...
4
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0answers
73 views

How to quickly identify participants responding randomly to self-report psychometric tests with many items?

Many psychological studies involve getting participants to answer a hundred or more closed ended questions. A standard context would be a personality test with 100 items where each item is answered on ...
2
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1answer
36 views

Publications in the social sciences or psychology based on freely available datasets?

There are a lot of datasets freely available across the web (see CV questions here, here, or here). Yet, I want the reverse: I am looking for a list of publications in the social sciences or ...
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0answers
24 views

Factor analysis without theoretical congruence

I've been working with certain personality theory, which I'm trying to measure in a sample of students. It's a foreign theory, so I created an instrument for my specific population. I got a Cronbach's ...
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0answers
32 views

Measure difference in answers on survey depending on item response options

For my thesis I sent out a questionnaire that has 10 questions. I set defaults: the first seven question had the default set to the desired answer and the last three questions had the default set to ...
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0answers
19 views

Estimating and using reliability metric with the same data

I'd like to know if it is reasonable to use the same set of data to estimate and use a reliability metric from repeated measures? I am mostly interesting by the minimal detectable change (MDC). But I ...
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1answer
47 views

Correlations within Factor in a psychometric measurement instrument

I am working with results of a psychometric test. There are twelve factors and each have three subfactors. My problem is that one of the subfactors correlates very highly 0.3 to 0.7 with subfactors of ...
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0answers
49 views

How to deal with floor effect

I am in the process of validating a five-items scale for measuring dependence on substance 'X'. I have collected data from 98 people who used the substance under consideration at least once weekly for ...
2
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0answers
43 views

Threshold for psychometric experiment with three (or more) possible choices

I'm running an experiment where subjects are viewing a stimulus, and they have to decide if the stimulus is brighter/darker/identical in respect to a standard image. Stimulus luminosity actually ...
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2answers
1k views

Can I combine several ordinal questions to create an index and/or composite measure?

I am using a survey that contains several questions about various dimensions of performance for policy research institutes. Here, performance in the policy arena is unpacked into things like: ...
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0answers
54 views

Estimates of regression coefficients at subject- vs group-level

For each of several subjects, I have mean reaction times for each of several stimuli. For each individual subject, I want to regress the RTs (as Y) against the stimuli (as X) and see if I get a slope ...
3
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0answers
155 views

What is the relationship between scale reliability measures (Cronbach's alpha etc.) and component/factor loadings?

Let's say I have a dataset with scores on a bunch of questionnaire items, which are theoretically comprised of a smaller number of scales, like in psychology research. I know a common approach here ...
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2answers
634 views

What criteria must be met in order to conclude a 'ceiling effect' is occurring?

According to The SAGE Encyclopedia of Social Science Research Methods… [a] ceiling effect occurs when a measure possesses a distinct upper limit for potential responses and a large concentration ...
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0answers
34 views

Testing face validity of a questionnaire

I would like to validate a questionnaire for my population, using a "think-aloud" (protocol analysis) method. The study looks at IT user satisfaction. Do you think my participants have to use the ...
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0answers
64 views

Principal component analysis, psychometrics, and number of items required

I saw that questions regarding sample sizes and PCA are asked here quite frequently. However, I was not able to find exactly the information I need. I plan to do a psychometric study and conduct a ...
0
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1answer
82 views

Eliminated items in Factor Analysis

I'd like to get your opinions on how to interpret items that had to be eliminated in factor analysis (FA). I've been researching consumer shopping motivations and ran a survey with 40 items, which ...
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3answers
291 views

What is the reasoning behind the formulae for the different standard errors of measurement?

McManus (2012) discusses the three standard errors of measurement and provides the following definitions. $SE_{meas} = SD \sqrt{(1 - reliability)}$ The standard error of measurement is an estimate ...
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4answers
262 views

How can there be a standard deviation of true scores?

Dudek (1979) describes the following formula as "the standard deviation of true scores when the observed score is held constant" (p. 337): $SE_{est} = SD \sqrt{(reliability × (1 - reliability))}$ ...
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17 views

Is there an extension of multinomial process models that can model several dependent variables?

In the setting of psychological experiments, where a categorical response has to be given, the same response can, in theory, be generated by different latent processes. For example, in an experiment ...
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2answers
2k views

How is the Spearman-Brown prophecy formula affected by questions of differing difficulties?

How are the results of the Spearman-Brown prophecy formula affected by having test questions of differing difficulties or raters who are easy or hard graders. One respected text says the S-B is ...
6
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3answers
594 views

How to correctly interpret a parallel analysis in exploratory factor analysis?

Some scientific papers report results of parallel analysis of principal axis factor analysis in a way inconsistent with my understanding of the methodology. What am I missing? Am I wrong or are they. ...
3
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1answer
118 views

Why change items which don't change Cronbach Alpha?

I am doing peer review on a paper submission for a journal, and I am somewhat out of my depth. The authors are developing a psychometric scale. They did a pilot study with 45 items. They measured ...
11
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3answers
5k views

Factor analysis of questionnaires composed of Likert items

I used to analyse items from a psychometric point of view. But now I am trying to analyse other types of questions on motivation and other topics. These questions are all on Likert scales. My initial ...
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2answers
319 views

Neutral option on Likert Scale

I would like to know how do we analyze or regard the Neutral response (such as Don't Know) in a questionnaire using the following Likert Scale: 1:Strongly Disagree 2:Disagree 3:Don't Know 4:Agree ...
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4answers
3k views

Is 0 a valid value in a Likert scale?

I have carried out my pilot study on language learning motivation using a 6 point Likert scale but from 0 (strongly disagree) to 5 (very much agree). I noticed a colleague in his survey used 1 to 6. ...
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0answers
52 views

Correlation significance test with standardized z scores

I am using spss I am looking at a criterion-validity concurrent design. I had to transform two groups performance ratings into z scores because there were differences in how raters rated them on the ...
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0answers
44 views

Map a normal distribution N(x,s) to an ordinal response variable

I am working on a simulation. I am going to extract a series of normally distributed values from a distribution $N(x,s)$ whose mean $x$ and variance $s$ is known. I want to pretend that such ...
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0answers
18 views

theoretical profile correlation

My data (n > 4000) contains the results of two separate tests (instruments). I have a profile made from likert scales for one of the instruments (S1, S2, ... S20). I want to find the corresponding ...