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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Best correlation test for an ordinal / nominal dataset

I have a data set in which I have, among others, two variables that measure the degree of stenosis in an artery. Both variables use the same classification which is ordinal (from 1 to 5, meaning 1 = "...
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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. ...
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Cronbach's Alpha

When calculating Cronbach's, would I include the reverse scores? I have 20 items, which 11 scores reversed. Would I just calculate the original scores?
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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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Can Crombach's alpha be used to argue for the representativeness of non-probability sample?

My understanding is that Crombach's alpha measures the reliability of survey items in a scale, when they are supposed to be a measure of a construct or concept. However, I'm reading a non-published ...
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30 views

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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Cronbachs alpha interpretation - what does var.r and med.r mean?

i have used the psych::alpha to find the cronbachs alpha values, but i cannot find any interpretation for some parts of the output, namely: ...
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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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Reliability estimation for questionnaire - is Cronbach's a applicable?

I am fairly new to scale analysis and I need to estimate the reliability and validity of a 5 item scale (5 questions, 2 have 4 choices abcd and 3 have 2 choices ab). The scale is supposed to be ...
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Cronbach's alpha for different items?

Can I perform a Cronbach's alpha test when the questions or items are completely different to each other as opposed to having similar questions written differently as a consistency measure?
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Can cronbach alpha be used for multiple choice questionnaires

I am trying to validate a questionnaire. It has four parts - knowledge, perceptions of vitamin D, perceptions of sun exposure and attitudes toward fortified supplements. Can I use cronbach for ...
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first factor saturation vs. general factor saturation

a simple explanation between these two in the context of reliability analysis, specifically Cronbach's alpha.
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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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413 views

Difference between Cronbach's alpha and Pearson's coefficient

I am creating an indicator for social development which includes variables of health, education and economy. Since I have many variables, I decided to remove some of them based on dominion expertise ...
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Low internal consistency

I am currently analysing 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 ...
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Factor analysis

I have a couple of questions on factor analysis using Stata. How to decide whether to use pf (principal factors, default), pcf (principal-components factor), ipf (iterated principal factor) or mle (...
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Analysis for Pilot Test Study Results

Is it possible to use Cronbach Alpha for a preliminary test study that has mostly dichotomous, nominal or ordinal responses or is this analysis method only specific for interval level responses such ...
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How to determine with confidence whether a latent construct is represented by a survey?

I recently reviewed a text designed to evaluate the validity of two surveys of self-care behavior. The authors used principal component analysis and Cronbach's alpha to valuate 2 surveys. Reading ...
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Is it correct to a total Cronbach´s alpha analysis to a tridimensional scale?

There´s a statement that says that Cronbach´s alpha assumes unidimensionality. In that sense, is it correct to calculate a global alpha? I mean, by including all 3 dimensions, and not by separating ...
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What is the difference between Cronbach's alpha and standardized Cronbach's alpha?

I found in the wiki article a definition of a standardized Cronbach's alpha but nothing is said what it is and about its relation to the original Cronbach's alpha: I found at What is Cronbach's ...
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How do you calculate a new scale from two given variables and then find out the cronbach-alpha?

The question concerns two variables with scores from a personality test, Ptest1 and Ptest2 with values from 60 participants from each variable. So how I can convert these two variables into a new ...
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220 views

Cronbach alpha with knowledge items?

I have a very specific question about the application of Cronbach's alpha to data with trichotomous responses (true-false-don't know). I have an acquaintance I'm helping replicate a study using a 45 ...
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Cronbach alpha and item selection

I am a relative novice when it comes to statistical analysis, so forgive me if my question is unclear, or simply stupid. I am also not a matemathician, as I work in social science research, but I have ...
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Interpreting low Cronbach's alpha value in CATPCA

I ran categorical principal component analysis (CATPCA) on the data that I collected through a questionnaire. The purpose of the questionnaire was to understand pedestrians intentions and attitudes ...
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What is the point of reporting split-half reliability together with Cronbach's alpha?

In several journal articles I read, autors report split-half reliability (Guttman formula obtained if questionnaire is splited into two parts: odd items and even items, usually) together with Cronbach'...
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271 views

Cronbach's alpha: how many digits to report?

I submitted my first paper to a peer-reviewed journal and got lots of feedback, questions and criticism back. One point was related to the number of digits I report for estimated values (e.g. for ...
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What is the relation between Cronbach's alpha and pair-wise correlation?

I generate multiple responses using a multivariate normal distribution with means of 5 and standard deviation of 2; I want ten responses and set the correlation between responses to be 0.5. ...
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410 views

Why does a factor need to be internally consistent?

I'm wondering exactly what the question says: Why does a factor (as linear combination of its items) need to be internally consistent? If I want to use a factor found in a factor analysis as a ...
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28 views

Psychometric properties on new sample with old questionnaire

When using a decades old inventory, questionnaire or factor from a questionnaire, is it important to retest the psychometric properties of this with the current sample, i.e. compute new Cronbach's ...
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Correlation between Likert scale independent variables and multiple categorical dependent variables

Based on the above diagram: My alpha for the independent variable is above 0.7 My Alpha is negative for the dependent variable. (I tried reversing items with negative words and the option of if ...
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Cronbach's alpha — optimum value is 1.00?

I have been brushing up on some stats and figure I'd have a look at Cronbach's alpha. As I understand it, a higher alpha coefficient means a greater interrelation between all the items. If items are ...
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166 views

How to combine different type of items of a questionnaire into a variable

I'm doing a research where I applied a questionnaire with 67 items measuring 5 variables. The issue is some questions are in Likert scale (0 to 10 and 1 to 5), some Yes, No, some open questions, ...
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Varying Likert Scale Categories

I hope that someone can help me with this question. I created a questionnaire that has different scales for each of the questions under one construct. Each of the questions still have a 5 point ...
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Are reliability and validity measures necessary for all parts of a survey

I am conducting analysis on a questionnaire which was a three-part study, not three separate studies. I asked the same exact set of validated scale questions for specific constructs for three ...
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108 views

do cronbach and factor analysis work together

I am writing a Master's Thesis based on a four construct model. I know I have to conduct a Cronbach's alpha test for reliability and I also need to conduct a confirmatory factor analysis for validity ...
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3k views

Does Cronbach's alpha reveal reliability information over and above the intraclass correlation coefficient?

I have seen in some papers that they have reported ICC as well as Cronbach's alpha. Does Cronbach's alpha provide more information about the reliability of a measured variable (e.g. heart rate at two ...
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Cronbach alpha application

I developed a questionnaire to measure some factors influence in decision using related literature and after some interviews. Now I have to validate and see how to distribute among the target group. I ...
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What does it mean if I have high Cronbach alpha, but poor results in Exploratory Factor Analysis

I have been given a survey to analyse. There are 50 questions, and about 400 respondents. I have calculated Cronbach alpha for the entire thing, and I get about 0.9. When I do factor analysis, I do ...
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130 views

How to calculate Cronbach's alpha for instrument that presents every test item twice in an administration?

Background I'm currently trying to calculate a Cronbach's alpha statistic for an instrument that has participants take every item twice during the administration. We are using a speeded mental ...
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2k views

Minimum sample size for Cronbach Alpha?

What should be the minimum number of people in a sample for finding cronbach alpha for: Questtionaire with 20 items (Likert scale) Test with 20 items (multiple choice) A sample of 10, 20 or 40 ? ...
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369 views

Cronbach Alpha for a test to be administered for two different samples

I need to calculate Cronbach's alpha for a test planned to be administered for two different samples. The test is planned to measure knowledge of these two samples, and these two samples vary on the ...
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64 views

When to calculate Cronbach's alpha for a paper?

I am doing my undergraduate thesis, and I wonder if I need to do the Cronbach's alpha from my data set, or if I should use the Cronbach's alpha from the commercial questionnaire I will use for this ...
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R results two different values of Cronbach Alpha

I'm a programmer and I needed to do a Cronbach's alpha method to compute statistics. I tried to write a code but I got two values of alpha: ...
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2k views

How to do a factor analysis with just one component?

I have done a questionnaire with six questions to measure engagement. This is the only component I measure. To make sure they measure just one component, I tried to run a Factor analysis with Direct ...
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359 views

Calculating Cronbach's alpha for pre-post scales separately or together?

I am measuring a self-efficacy (SE) score by measuring 7 sub-scales for pre and post intervention.For example, for a participant, I have the SE score by measuring 7 sub-scales before the intervention, ...
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138 views

Compute scales/subscales

My dissertation (psychology) is on the relationship between social connectedness and psychological distress. Essentially, I am combining 9 scales that broadly reflect social connectedness (loneliness, ...
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624 views

How to calculate alpha reliability of a scale (factor) when it is expressed in factor scores?

I am doing a Principal Axis Factor Analysis, I found two factors and saved the factor scores for each, using the regression approach (as in the SPSS option by default). My question is, how do I ...
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278 views

Factor analysis and cronbach's alpha

My research work is based on a questionnaire which includes all types of questions ordinal as well as nominal but 80% of the questions are based on likert scale 1-5. My question is whether Cronbach's ...