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

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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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15 views

Where I can find resources to learn how to calculate the sample size representativeness, and realiability and validity of questionnaires?

I'm totally newbie in psychometrics but starting from a research paper with full data I would like to understand: how to calculate if the sample size is representative; how to calculate reliability ...
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1answer
26 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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1answer
61 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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11 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 ...
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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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9 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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0answers
17 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
134 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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29 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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39 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
55 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
28 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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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
52 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 ...
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0answers
24 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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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
78 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 ...
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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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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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37 views

Identifying the number of conditions by which variance components will be divided in Generalizability Theory using QME R package

I'm using QME R Package (can be downloaded from here) to calculate Generalizability ...
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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 ...
2
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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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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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0answers
60 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 ...
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0answers
50 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 ...
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1answer
48 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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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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65 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 ...
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1answer
84 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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0answers
168 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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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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3answers
686 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. ...
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1answer
123 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 ...
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2answers
342 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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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 ...
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2answers
692 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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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
19 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 ...
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86 views

How can IRT-Models be understood in GLM/ SEM Framework? (Predict Learning with added Paradata-Covariates)

I'll be working with data from an intelligent tutor system similar to one studied in the KDD-Cup 2010 on student performance prediction and plan to use IRT models to infer item and ability parameters. ...
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1answer
147 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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3answers
227 views

Can statistics really be used in education to determine test scores?

I am a middle school teacher. My district prides itself on having the kids take 3 tests during the year to predict their score, and my teaching, on "the real test" at the end of the year. My question: ...
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2answers
310 views

Identification of useless questions from a questionnaire

I'm developing a questionnaire. To improve its reliability and validity I want to use statistical methods. I want to eliminate questions whose answers are always the same. This means that nearly all ...
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4answers
711 views

If a measure is valid (but not necesarily reliable), can it be consistently replicated?

I had this question on an exam, and I was positive that the answer was A. The Beck Depression Inventory is a scale intended to measure depression levels, with higher scores indicative of higher ...
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1answer
116 views

Several items for one construct

I am a dummy in statistics but need to accomplish some simple survey analyses. My question is: if I have several questions (items) for one construct (say, questions JS1-JS3 for job satisfaction) with ...
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1answer
155 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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1answer
192 views

Calculating total score for a scale including polytomous and dichotomous items [duplicate]

I have a variable that is measured using a 13-item, 4-point Likert scale with the exception of one item (yes $=1$, no $=2)$. How can I calculate the total score for this variable?
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2answers
68 views

Can I turn a latent variable be treated as an observed variable?

I am a doctoral candidate and for my dissertation research I am using two standardized scales as independent variables. Because these have not been used with my particular population, I needed to do ...
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1answer
195 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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393 views

Intra- and inter- observer error, and the intra-class correlation coefficient (ICC)

I have 3 observers, who each perform multiple observations in which they count a phenomenon. I'm trying to quantify both inter- and intra- observer error for this study. I'm new to this and am finding ...