Reliability Cronbach's alpha

Reliability is a fast, fully offline app that measures the internal consistency of your questionnaire scale - Cronbach's alpha, standardized alpha, item statistics, and the alpha-if-deleted diagnostic.

Type your respondents x items grid and instantly see which items belong together, and which single item is quietly dragging your scale's reliability down.

WHAT'S INSIDE

Items
The signature chart - alpha-if-deleted bars with a reference line at the scale's overall alpha, so the item worth cutting jumps out at a glance.

Data
An editable respondents x items grid (add or remove items and rows) with Cronbach's alpha, standardized alpha, mean inter-item correlation, and per-item statistics, all updating live.

Concept
A plain-English walkthrough of what reliability means, how to read alpha, item-total correlation, and alpha-if-deleted - with the formulas rendered in offline KaTeX.

Item-total
Corrected item-total correlation bars for every item, so you see exactly how well each one fits with the rest of the scale.

Simulate
Knobs for item consistency, item count and respondents - watch alpha climb as consistency and item count increase.

Examples
Ready-made scales - a good scale, one bad item, a weak scale, and a six-item survey - that load with one tap.

WHY RELIABILITY

- 100% offline - your data never leaves your device
- No account, no sign-up, no clutter
- Clean, distinctive interface built for students, researchers, and survey designers
- Cronbach's alpha, standardized alpha, item-total correlation, and alpha-if-deleted - the full diagnostic toolkit, not just one number
- Input is never lost - your whole dataset is saved automatically

Whether you're a student learning what Cronbach's alpha actually measures, a researcher checking a scale before publishing, or a survey designer hunting for the one item that's hurting reliability, Reliability shows you the whole picture in one glance.