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THE FEUTEX TOOLKIT

Cronbach Alpha from Variance Summaries

Estimate internal consistency from item count, summed item variances, and total-score variance.

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01 Your input
02 Your result
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FormulaAlpha = k/(k-1)*(1-items/total)
Sources and model references

Made for real tasks

  • Estimate internal consistency from item count, summed item variances, and total-score variance.
Explore step-by-step workflows →

Worked example

Inputs

Item count
10 count
Sum of item variances
12 number
Total score variance
40 number

Expected results

Alpha
0.7777777778 number

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

  1. Enter item count, sum of item variances, total score variance.
  2. Use the displayed units and confirm the model assumptions.
  3. Calculate and compare the outputs against your input scenario.

Try this example

{
  "k": 10,
  "items": 12,
  "total": 40
}

Accuracy and scope

Alpha is not proof of unidimensionality or validity. All variances must come from the same scored items and respondents.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.