Psychometrics has evolved as a subfield of psychology to become the science of measurement of unobservable individual characteristics.
1
vote
0answers
32 views
how to analyze necessary/sufficient relationship?
Good day!
I'm a second year psych grad student. From my fascination with formal logic, I wondered (just personal; not homework) about how to statistically establish necessary/sufficient ...
0
votes
2answers
86 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:
...
1
vote
0answers
22 views
What coefficient could I use to calculate the relative difficulty of a test in relation to others using only mean and population standard deviation?
I have a series of tests, all of them of different difficulty, and from each of them I get an average score and a population standard deviation; e.g:
...
3
votes
1answer
77 views
Sampling considerations in psychometric applications of item response theory
Background
I have developed a recent interest in Item Response Theory and its applications. I am studying clinical psychology and am most interested in polytomous models aimed at modelling ...
0
votes
1answer
687 views
Likert scale and yes/no calculation of one score
My survey is based on observations and interviews. The observation questions are yes/no type questions and interview questions are 4 points.
1 = never, 2 = sometimes, 3 = usually, and 4 = ...
3
votes
1answer
61 views
IRT/Rasch modeling with very large N
I want to fit a 1-parameter IRT model on a questionaire with 15 questions and about six million people. Considering the large N, standard errors aren't essential. It looks like the IRT world is sort ...
1
vote
1answer
241 views
Predicting dependent variables where independent variables are samples with differing sample size
Is there a standard method of dealing with independent variables, where they are samples from a known distribution, and the sample sizes differ from sample to sample?
I'll give an example of what I ...
0
votes
1answer
30 views
EFA on R: Classifying Observations
I am newbie for R and Stats. I am using EFA in R [psych library] to identify the latent factors underlying my data. I got a reasonable amount of factors matching my purpose.
My question is once I ...
1
vote
2answers
72 views
What factors do I have to consider when deciding if creating a composite score using four t-scores is defensible psychometrically?
Edit:
I've conducted an item analysis on four variables - two quizzes and two psychological attributes, namely emotional intelligence and happiness. Its a within-subject design with students as ...
5
votes
4answers
2k views
What are the primary differences between z-scores and t-scores, and are they both considered standard scores?
We are currently converting student test scores in this manner :
( ScaledScore - ScaledScore Mean ) / StdDeviation ) * 15 + 100
I was referring to this ...
11
votes
3answers
3k views
How to get started with applying item response theory and what software to use?
Context
I have been reading about item response theory, and I find it fascinating. I believe I understand the basics, but I am left wondering how to apply statistical techniques related to the area. ...
3
votes
1answer
48 views
EFA clearly supports one-factor, measure is internally consistent, but CFA has poor fit?
I am exploring the psychometric properties of a 10-item self-report measure. I have about 400 cases in two independent samples. The items are completed on 4-point Likert scales. An EFA clearly ...
2
votes
1answer
86 views
Comparing two logit or probit curves using a single parameter
I've conducted a psychological experiment on the same subject, under two different condition. For each condition I've collected the number of correct and wrong answer for each stimulus (number of ...
3
votes
1answer
479 views
4 point and 5 point Likert scales in a new questionnaire
I'm looking to confirm whether having a 4 point Likert Scale for some constructs, and a 5 point Likert scale for other constructs will be suitable when developing a questionnaire?
I have 7 constructs ...
2
votes
1answer
152 views
Using total score from multi-scale instrument in structural equation modeling
I wonder if you can help me to get the right answer to a question about structural equation modeling. Imagine someone trying to validate a questionnaire using component factor analysis that ...
2
votes
2answers
92 views
How do I analyze a z-score to determine a difference?
My data are in SPSS. I teach in a nursing program.
During their junior year, 68 students participated in a simulation scenario for heart failure. They were by rated by observers (0/1, did not do/did ...
4
votes
1answer
216 views
IRT in R: Does anyone know of an IRT item calibration function that can cope with NA's?
I have a dataset that looks like this.
...
3
votes
1answer
546 views
Which package to use for convergent and discriminant validity in R?
I am new to R and want to assess validity of some scales using R. Is there a package that I can use to test for convergent and discriminant validity in R?
2
votes
1answer
243 views
Omega vs. alpha reliability
I wonder if someone can explain what is the main difference between omega and alpha reliabilities?
I understand an omega reliability is based on hierarchical factor model as shown in the following ...
3
votes
3answers
654 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 ...
1
vote
0answers
180 views
Which correlation analysis is appropriate for binary and ordinal variables?
Violin players were asked to rate 5 violins from least to most rich on a [0 1], 0.05-increment scale, ...
8
votes
2answers
1k views
Recommended procedure for factor analysis on dichotomous data with R
I have to run a factor analysis on a dataset made up of dichotomous variables (0=yes, 1= no) and I don´t know if I'm on the right track.
Using tetrachoric() I ...
6
votes
4answers
5k views
How to compute correlation between/within groups of variables?
I have a matrix of 1000 observations and 50 variables each measured on a 5-point scale. These variables are organized into groups, but there aren't an equal number of variables in each group.
I'd ...
10
votes
4answers
946 views
Is it appropriate to treat n-point Likert scale data as n trials from a binomial process?
I've never liked how people typically analyze data from Likert scales as if error were continuous & Gaussian when there are reasonable expectations that these assumptions are violated at least at ...
1
vote
0answers
40 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 ...
1
vote
3answers
473 views
Is there a package in R which implements the weighted maximum likelihood method?
Is there a package in R which implements the weighted maximum likelihood method (Warm, 1996) for estimating the person parameters in Rasch Models?
2
votes
1answer
96 views
Item information in IRT with item covariates (linear logistic test model)
Short question: How does the calculation and interpretation of IRT item information and test information change in the presence of item properties?
Long question: There's a variation on IRT called ...
1
vote
1answer
428 views
Understanding signficant interaction with non-significant main effects [duplicate]
Possible Duplicate:
How to compute significant interaction estimates when main effect is not significant?
I am an applied linguist and I am modelling responses to a vocabulary test taken by ...
1
vote
0answers
254 views
How to validate a survey when using Likert scale?
I have developed a very simple survey to measure the attitudes of students toward science fairs. It makes use of the Likert Scale and Open Ended Questions. Do you have a recommendation for the type ...
2
votes
1answer
71 views
How to equate questionnaires with different response scales
I'm trying to help out a not-for-profit organization and made an error that I'm trying to fix. They've been doing a non scientific survey of their Board of Directors for a number of years regarding ...
1
vote
1answer
94 views
How is Item Response Theory (IRT) called for continuous response?
I would like to model my problem using something similar to Item Response Theory - but my responses are not binary - they are continuous in [0;1].
How are these models/the research field called?
4
votes
2answers
66 views
How to deal with the cases when participants gave rating of 2.5 or 4.5 on a 1-5 scale?
Because this was done during the interview, the participants just spoke out their rating rather than marked it done on the paper: they sometimes say "I think it is between 2 and 3" or "I give it 4 or ...
2
votes
1answer
68 views
Item information in IRT
According to item information curves, item information for a 2PL IRT model is
$I(\theta)=a^2_i p_i(\theta) q_i(\theta)$
To determine $p_i(\theta)$ and $q_i(\theta)$, do you just use the observed ...
5
votes
3answers
890 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. ...
0
votes
1answer
42 views
Test of symptom severity equality / symptom configuration equality
We have a questionnaire measuring 9 clinical symptoms. The sum scores simply adds all these symptoms up. Symptoms are ordered (0,1,2,3), and pretty strongly skewed (lots of 0s).
1) First, we want to ...
4
votes
1answer
135 views
Internal consistency reliability in item response theory models
How can internal consistency reliability of a test and of individual test items be quantified in Item Response Theory models? I know I can resort to Classical Test Theory, Cronbach's alpha, and other ...
0
votes
1answer
756 views
Interpreting AIC and BIC fit
I'm writing a CFA paper, and I have run into some trouble interpreting the AIC and BIC. This is my first paper using continuous variables, thus the first time I will be reporting these fit statistics ...
2
votes
0answers
72 views
Testing graded response model thresholds for significance?
I have a data set in which two raters have each rated N samples using a 5-point ordinal rating scale. My primary interest is in whether these two raters make significantly different use of those ...
3
votes
0answers
97 views
Are discrimination parameters in two-parameter IRT models only specific to items?
Discrimination parameters in two-parameter model from IRT are usually considered item parameters.
But I've come to doubt it.
Think about psychophysics; for example, detecting luminance.
I don't ...
3
votes
1answer
336 views
Designing and validating a Likert-type scale with odd or even response categories
As part of an advisory team in my educational institution for undergraduate nurses, I (among others) have been assigned to design a questionnaire that will assess students' and academic staff's ...
2
votes
0answers
164 views
Dealing with poor fit in an Item Response Theory model
I'm studying an online course with about 3000 students who each took several quizzes and I'm trying to apply Item Response Theory (using the ltm package in R) to model the questions, determine which ...
1
vote
0answers
149 views
Obtaining factor scores from a factor analysis of mixed types (both ordinal and scale) variables
I have to analyze a data set having both ordinal and scale variables. What I was trying to do was to factor analyze the data. The data was in SPSS. But I think SPSS factor analyzes the data by ...
7
votes
1answer
208 views
What am I measuring when I apply a graded response model to the “Hunting of the Snark” dataset?
In another question, I asked about the statistical validity of StackExchange's "Hunting of the Snark" dataset, and whether or not we could draw any conclusions from its results. I measured a few ...
2
votes
1answer
67 views
Ordinal reliability for small examinee population
Biswas considers "a classical-type linear model of observed score ($X$), true score ($T$), and random error ($E$)" and asserts
... in test theory, interpretation of $\rho_{TX}$ has an intuitive ...
4
votes
3answers
241 views
$\chi^2$ tests to compare the fit of large samples logistic models
Does anyone know of any $\chi^2$ tests to compare the fit of logistic models which factor out the sample size? I'm dealing with a very large sample and I fear the significant $\chi^2$ test I get when ...
2
votes
0answers
226 views
Fixing error variance in a path analysis to model measurement error in scales using sem package
I want to construct a path analysis model that can account for measurement error in totally aggregated parcels, which refer to parcels where all of the items in a scale are summed or averaged. If I am ...
1
vote
2answers
224 views
Rules of thumb for creating composite scales
Normally when I create an index I basically just take the or averages of the individual variables that comprise the index. But I'm wondering if one should / could not, take the product?
E.g., a scale ...
6
votes
1answer
708 views
Looking for a step through an example of a factor analysis on dichotomous data (binary variables) using R
I have some dichotomous data, only binary variables, and my boss asked me to perform a factor analysis using the tetrachoric correlations matrix. I’ve previously been able to teach myself how to run ...
0
votes
0answers
161 views
Survey Data - Factor Analysis
I was hoping you could help with this question. I have a survey, a 30-item instrument. I've got 18 responses back from this.
I also have a paper in which they've done a principal axis factor ...
2
votes
1answer
182 views
VSS criterion for the number of factors (in R's psych package)
I'm working from caracal's great example conducting a factor analysis on dichotomous data using R and I'm now struggling to understand the difference between VSS complexity 1 and VSS complexity 2 in ...
