# Questions tagged [cronbachs-alpha]

Cronbach's $\alpha$ is an estimate of the reliability (specifically, of one its aspect called internal consistency or item-item homogeneity) of a unidimensional test, a construct. It is used mostly in psychometrics and occasionally in other disciplines.

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### What is known about the (in)efficiency of true score variance estimation?

In classical test theory, an observed score $X$ is defined as $$X = T + E$$ where $T$ represents the individual true score and $E$ represents the individual error score. In this context $T$ may be ...
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### Mean score of the Composite Variable

I have three items(Likert scale from 5 to 1) measuring opportunity recognition. I was getting negative cronbachs alpha value. Hence, I reverse-coded and got the Cronbach's alpha of 0.83. I will be ...
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### How to calculate reliability of difference scores?

I am trying to calculate the reliability of a difference score. Specifically, the data have, for each participant, scores for 10 items in Condition X (1s and 0s), as well as 10 different items in ...
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### Cronbach's alpha for knowledge pretest-posttest / control and treatment groups

I am having trouble finding clear answers to these specific questions about calculating Cronbach's alpha. For my dissertation study, I conducted a teaching intervention. I administered a pretest and ...
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### Cronbach alpha - descriptive statistics

I researched thinking styles based on Sternberg's Investment Theory. I used a TSI questionnaire that measures preferences in thinking styles. The problem is that I got low scores of Cronbach's alpha ...
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### Cronbach alpha for non-Likert & Likert survey

I have a thesis ongoing and I have a survey that needs for reliability testing. I was advised to do a Cronbach's alpha test. My survey consists of two parts: Part 1: All questions have varying number ...
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### How do we decide the sample size we need for ensuring reliability for a test?

There is a test consisting of 6 questions and additional sub-Qs. The test was translated into another language and the questions were adapted, but the reliability of the test was never assessed. The ...
1 vote
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### Measuring the reliability of a survey data

I have a survey data and I applied KR20 on it. The KR20 score is 0.63 which means this survey result is not consistent and reliable, at least not in a reliable range with the definition of a reliable ...
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### Visualize Cronbach's alpha in R Ggplot scatterplot as a regression line? [closed]

I'm looking for a way to make a scatterplot of the correlation between two questionnaires using Cronbach's alpha: Data: ...
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### Negative Cronbach's alpha – recode data, or use another method?

Below is a made up scenario to exemplify my issue. I have two questionnaires asking individuals how much headache they have compared with 7 days ago. The scale is from much less through little less, ...
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1 vote
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### Cronbachs alpha for items with different scales

I have a sample size of N=63 and 6 items measuring risk tolerance. Now, I want to calculate Cronbachs alpha, however, the 6 items have different scales. For example, the first item has a scale from 1-...
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### When running a reliability analysis (using Cronbach's alpha) in SPSS, what does "scale" refer to? Do I have to compute a scale explicitly beforehand?

Is the scale meant to represent the sum of responses (each response is an element of, say, the set {1, 2, 3, 4, 5}) of a case (an individual) to a set of questions (items)? And is a "scale mean&...
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### IRT: What is enough information? And can a test provide too much?

I was wondering what makes for a good test information value in IRT, and came across this: Reliability: Item and test information functions graphically reflect how reliably the individual items and ...
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### How to use Cronbach's Alpha?

Is it appropriate to use Cronbach's Alpha for nominal variables? I have 20 nominal variables (two dimensions with 10 questions each) that ask about the characteristics of work performance. The ...
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### Fleiss' Kappa v. Cohen's Kappa v. Cronbach's Alpha

I am working on a project that compares two methods of assessing whether certain topics come up in a therapy session. I am comparing a checklist full of dichotomous (y/n) items completed by an ...
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### Alternative to Cronbach's alpha if $n$ is too small for McDonald's omega?

I have a very high Cronbach's Alpha of $0.966$ (and composite reliability of $0.969$). My questionnaire has a 1-factor-structure, which makes it compatible with Cronbach's Alpha, but it has 22 items. ...
1 vote
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### Cronbach's alpha and reverse-scored items

When calculating Cronbach's $\alpha$, would I include the reverse scores? I have 20 items in total, including 11 reverse-scored items. Would I just calculate the original scores?
1 vote
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### Cronbach's Alpha with repeated missing values

I would like to use Cronbach's Alpha to check the fiability or internal consistency of a cognitive task. The task has a certain number of trials which were coded with zeros (incorrect trial) and ones (...
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### Adjust alpha when switching from one-tailed t-test to two-tailed

I started with a hypothesis that says e.g. A is larger than B which would usually call for a one-tailed t-test. But after acquiring the data it turns out that the effect seems to be contrary to my ...
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### Should reliability test (cronbach alpha) include missing values?

I am currently doing a reliability test for my questionnaires with 34 respondents. However, there are some missing values in the questionnaires which I'm not sure whether I need to include or exclude ...
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### Is it always needed to do a validity test for variables?

Let's say I have one variable called "perceived image", which is measured with 6 items (questions) that I adapted from previous literature. If I have a Cronbach's alpha > 0.7 (for reliability), do I ...
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### Unidimensionality in IRT

I recently came across the definition of unidimensionality (in the context of IRT and internal consistency reliability, specifically Cronbach's alpha). Johnsosn (2007) states that There is a one-...
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### item-total correlation vs. inter-item correlation

I am assesing the reliability and validity of an 16-item multuiple choice test supposed to test language skills. Cronbach's apha is "questionable" with .65. I am having troubles interpreting the ...
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### Cronbach's Alpha of Likert Item

My questionnaire consists of ten 5-point scaled Likert items. If the Likert items have a good Cronbach alpha, is it ok to take the average score of 10 items?
1 vote
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### Low internal consistency

I am currently analyzing the data for a survey I have completed. In doing so, one question is quite simple (nominal) and require a typical “I do/I do not” and “I do not/I do” response from the ...
1 vote