--- title: Item Reliability Analysis description: The Item Reliability Analysis estimates the reliability or internal consistency of a set of variables. It is commonly used to assess the reliability of questions in a survey or test. The procedure calculates Cronbach’s alpha for the entire set of variables and when omitting each variable one at a time. A lower confidence bound for alpha may also be calculated. image: https://www.statgraphics.com/hs-fs/file-2396888304-png/Graphs/reliability_analysis_graph-254298-edited.png --- [![stat19plain-01-1](https://www.statgraphics.com/hs-fs/hubfs/stat19plain-01-1.png?width=2324&name=stat19plain-01-1.png "stat19plain-01-1")](https://www.statgraphics.com) - [Products](https://www.statgraphics.com/product) - [Learn](https://www.statgraphics.com/statistics-library) - [Training](https://www.statgraphics.com/training-and-consulting) - [Product](https://www.statgraphics.com/product) - [Centurion XVIII](https://www.statgraphics.com/centurion-xvii) - [Sigma Express](https://www.statgraphics.com/statgraphics-sigma-express) - [Online](https://www.statgraphics.com/statgraphics-stratus) - [Web Services](https://www.statgraphics.com/statgraphics-web-services) - [Learn](https://www.statgraphics.com/statistics-library) - [Statistics Library](https://www.statgraphics.com/statistics-library) - [Six Sigma & Lean](https://www.statgraphics.com/six-sigma-lean) - [Instructional Videos](https://www.statgraphics.com/instructional-videos) - [Applications/ Case Studies](https://www.statgraphics.com/application) - [Training & Consulting](https://www.statgraphics.com/training-and-consulting) - [Statpoint Seminars](https://www.statgraphics.com/statpoint-seminar) - [Statpoint Instructors](https://www.statgraphics.com/statpoint-instructor) - [Training Partners](https://www.statgraphics.com/training-partners) - [Webinars](https://www.statgraphics.com/webinars) - [Support](https://www.statgraphics.com/customer-support-overview) - [Blog](https://www.statgraphics.com/blog) - [Store](http://store.statgraphics.com) ### Statgraphics ## [Centurion](https://www.statgraphics.com/centurion-overview) #### [LEARN MORE](https://www.statgraphics.com/centurion-overview) ### Statgraphics ## [Sigma *express*](https://www.statgraphics.com/statgraphics-sigma-express) #### [LEARN MORE](https://www.statgraphics.com/statgraphics-sigma-express) ### Statgraphics ## [*Stratus*](https://www.statgraphics.com/statgraphics-stratus) #### [LEARN MORE](https://www.statgraphics.com/statgraphics-stratus) ### Statgraphics ## [Web Services](https://www.statgraphics.com/statgraphics-web-services) #### [LEARN MORE](https://www.statgraphics.com/statgraphics-web-services) ## [Statistics Library](https://www.statgraphics.com/statistics-library) #### [LEARN MORE](https://www.statgraphics.com/statistics-library) ## [Six Sigma & Lean](https://www.statgraphics.com/six-sigma-lean) #### [LEARN MORE](https://www.statgraphics.com/six-sigma-lean) ## [Instructional Videos](https://www.statgraphics.com/instructional-videos) #### [LEARN MORE](https://www.statgraphics.com/instructional-videos) ## [Applications/ Case Studies](https://www.statgraphics.com/statistical-applications) #### [LEARN MORE](https://www.statgraphics.com/statistical-applications) ## [Statgraphics Seminars](https://www.statgraphics.com/statpoint-seminar) #### [LEARN MORE](https://www.statgraphics.com/statpoint-seminar) ## [Statgraphics Instructors](https://www.statgraphics.com/statpoint-instructor) #### [LEARN MORE](https://www.statgraphics.com/statpoint-instructor) ## [Training Partners](https://www.statgraphics.com/public-seminar) #### [LEARN MORE](https://www.statgraphics.com/public-seminar) ## [Webinars](https://www.statgraphics.com/webinars) #### [LEARN MORE](https://www.statgraphics.com/webinars) ![bloglogo3-01](https://www.statgraphics.com/hs-fs/hubfs/bloglogo3-01.png?width=400&height=101&name=bloglogo3-01.png "bloglogo3-01") Jan 26, 2015, 6:26:54 AM ## [Item Reliability Analysis](https://www.statgraphics.com/blog/item-reliability-analysis) ![](https://www.statgraphics.com/hs-fs/file-2017572828-jpg/website-assets/neil-polhemus.jpg?width=50&name=neil-polhemus.jpg) By: [Dr. Neil Polhemus](https://www.statgraphics.com/blog/author/dr-neil-polhemus) Published under: [Cronbach's alpha](https://www.statgraphics.com/blog/topic/cronbachs-alpha), [statistics](https://www.statgraphics.com/blog/topic/statistics), [reliability analysis](https://www.statgraphics.com/blog/topic/reliability-analysis) The *Item Reliability Analysis* estimates the reliability or internal consistency of a set of variables. It is commonly used to assess the reliability of questions in a survey or test. The procedure calculates Cronbach’s alpha for the entire set of variables and when omitting each variable one at a time. A lower confidence bound for alpha may also be calculated.  ![reliability_analysis_graph-254298-edited](https://www.statgraphics.com/hs-fs/file-2396888304-png/Graphs/reliability_analysis_graph-254298-edited.png?width=525&name=reliability_analysis_graph-254298-edited.png)     [![Watch The Video](https://no-cache.hubspot.com/cta/default/402067/8ac38c98-bb0c-40b2-8ab7-e246a3354821.png)](https://cta-redirect.hubspot.com/cta/redirect/402067/8ac38c98-bb0c-40b2-8ab7-e246a3354821)   # Something to say? ### Subscribe to our blog: The Statgraphics Blog is designed to share knowledge and ideas amongst all members of the Statgraphics community. We welcome your comments and suggestions regarding the topics posted. In addition, let us know if there are other topics that you would like to discuss. 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