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

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4answers
6k 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 ...
2
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1answer
115 views

Assessing effect of intervention where aptitude tests used in pretest and posttest have some overlapping and some distinct items

In my research there is a pretest, and a treatment followed by a posttest. The pre and the posttests are similar but not exactly the same. A few questions were changed between the pre and posttests ...
4
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1answer
114 views

Testing the importance of an item among a finite set of items

Consider the following survey question: Q: How would you classify the importance for you of the following 5 items: A B C D E Assign to each item a number ...
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2answers
2k views

Assessing reliability of a questionnaire: dimensionality, problematic items, and whether to use alpha, lambda6 or some other index?

I am analyzing scores given by participants attending an experiment. I want to estimate the reliability of my questionnaire which is composed of 6 items aimed at estimating the attitude of the ...
9
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2answers
2k 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 ...
5
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1answer
5k views

Intraclass correlation coefficient vs. F-test (one-way ANOVA)?

I'm a little confused regarding the intraclass correlation coefficient and one-way ANOVA. As I understand it, both tell you how similar observations within a group are, relative to observations in ...
7
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4answers
8k 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 ...
3
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0answers
1k views

How to carry out a Likert scale analysis?

Context: My research aims to assess whether parents who have been involved in a relationship with a social worker are at higher risk of child abuse/neglect. I am trying to establish whether there ...
21
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2answers
633 views

Detecting patterns of cheating on a multi-question exam

QUESTION: I have binary data on exam questions (correct/incorrect). Some individuals might have had prior access to a subset of questions and their correct answers. I don’t know who, how many, or ...
2
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2answers
346 views

What does it mean if there is a correlation between underlying factors in factor analysis?

I'm running an EFA using orthogonal/varimax rotation, and assigning variables to a factors based on maximum load (so only each variable only gets one factor). I then want to validate the model using ...
6
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3answers
903 views

Validating an existing questionnaire into another language

I am doing research and trying to use a questionnaire that is available in English in another language. Is there a systematic approach for validating a questionnaire in another language? What ...
3
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1answer
200 views

Is there a way to place a priori constraints on item difficulty under item response theory?

I have a dataset where the difficulty level of my items and skill of my participants is unknown, but I would like to be able to extract some metric of how individual participants do on the test. What ...
4
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2answers
394 views

When do you consider a variable is a latent variable?

The problem is to define when a variable might be considered as a latent variable. I am interested in how to describe a latent variable, and what are the properties of latent variables. My twofold ...
2
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1answer
2k views

Internal reliability for an ordinal scale

My teacher is asking whether it is possible to look at the Cronbachs's alpha when looking at the internal reliability of an ordinal scale. She thinks, because you use the mean of it, it is not ...
1
vote
2answers
178 views

Establishing that the population sampled of two separate surveys is the same

I have two surveys of two separate populations (I don't know that they are necessarily distinct, but they are from two different databases) that ask a similar set of questions. Some questions are ...
6
votes
2answers
264 views

Estimating the probability of a person getting a question right

We need to estimate the probability of a person getting a question right for a given content area given his history of getting questions in the same content area right in the past. We would also ...
8
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4answers
1k views

Can one validly reduce the numbers of items in a published Likert-scale?

[edits made in response to feedback- thanks :-) ] Doh! More edits! Sorry! Hello- I am doing some rather rough and ready data collection with a survey sent out to healthcare staff using a published ...
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3answers
3k views

Validating questionnaires

I am designing a questionnaire for my dissertation. I am in the process of validating the questionnaire I have applied a Cronbach's alpha test to the initial sample group. The responses to the ...
6
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2answers
955 views

Item Analysis for an R newbie

I am trying to assess a 20-item multliple choice test. I want to perform an item analysis such as can be found in this example. So for each question I want the P-value and the correlation with the ...
3
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1answer
1k views

Data transformation for Principal Components Analysis from different Likert scales

I have data from a survey comprised of several measures that used different Likert-type scaling (4-, 5-, and 6-point scales). I would like to run a principal components analysis using the data from ...
3
votes
2answers
327 views

The best measure of reliability for interval data between 0 and 1 [closed]

I have 6 sets of interval data each of which between 0 and 1. Each set, calculated by a computer program, is related to the degree of similarity between some sounds (pairwise). What do you think in ...
14
votes
2answers
9k views

Inter-rater reliability for ordinal or interval data

Which inter-rater reliability methods are most appropriate for ordinal or interval data? I believe that "Joint probability of agreement" or "Kappa" are designed for nominal data. Whilst "Pearson" and ...
3
votes
1answer
527 views

R package ltm: How to manipulate title on item response category characteristic curve plot

I have conducted an IRT analysis using package ltm in R 2.10. fit1 <- grm(data) When producing plots of item response characteristic curves (ICCs), ...
6
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3answers
2k views

Differences between tetrachoric and Pearson correlation

Currently I'm analysing around 300 items in the field of education. I'm interested in the dimensionality of the dataset. So I compute a matrix of tetrachoric correlation. The goal is to do a factor ...
2
votes
2answers
800 views

Confidence intervals on differences in choices in a GEE framework: methods and alternatives?

Say we have 5 items, and people are asked which item they like. Multiple answers are possible, but also no answer is possible. The people are categorized according to factors like gender, age, and so ...
3
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3answers
2k views

Classification after factor analysis

I have analysed several dimensions in a survey. Each part of the survey represents a theoretical dimension and is analysed with factorial analysis. I want to use scores from factor analysis to do a ...
10
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5answers
1k 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 ...
11
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3answers
3k 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 ...
3
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3answers
296 views

Quantitative methods and statistics conferences in psychology?

What are the most significant annual conferences focusing on quantitative methods in psychology? This could include but is not limited to psychometrics, mathematical psychology, and statistical ...
5
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4answers
675 views

FA: Choosing Rotation matrix, based on “Simple Structure Criteria”

One of the most important issues in using factor analysis is its interpretation. Factor analysis often uses factor rotation to enhance its interpretation. After a satisfactory rotation, the rotated ...
7
votes
2answers
666 views

Reliability in Elicitation Exercise

I am trying to calculate the reliability in an elicitation exercise by analysing some test-retest questions given to the experts. The experts elicited a series of probability distributions which were ...