# Correlation Confidence Intvls

> Correlation Confidence Intvls (iPhone/iPad app by MSYapps.)

- Source: https://appshunter.io/ios/app/correlation-confidence-intvls/id620244794 (this page in markdown: same URL + `.md`)
- Developer: [MSYapps](https://appshunter.io/developer/458482419)
- Category: Utilities, Education
- Price: $0.99
- Age rating: 4+
- Requires: iOS 12.4 · 2 MB
- Languages: American English
- Released: 2013-03-20
- Data updated: 2026-05-19
- User reviews in markdown: https://appshunter.io/ios/app/correlation-confidence-intvls/id620244794/reviews.md

## What is Correlation Confidence Intvls?

Correlation is a quantitative tool commonly used by researchers to separate data sets into independent subgroups. Hypothesis testing determines whether or not the subgroups are numerically distinct. The degree to which the researcher can say the subgroups are distinct depends upon the overlap between the subgroups measured by the confidence interval estimates. The confidence interval estimates reflect the reality that there are errors in all quantitative estimates.

If correlation estimates were normally distributed, estimates of confidence intervals would be straightforward. However, correlation estimates are bound within the range of –1.0 to +1.0. The common technique devised by R.A. Fisher involves a nonlinear transformation of correlation functions into random variables that are approximately normal. The technique is known as Fisher's z-transformation and is formally expressed as ρ = tanh(z), where tanh( ) is the hyperbolic tangent function.

More simply, the transformed standard error, z, is defined as z = (1/2) ln[ (1 + ρ) / (1 – ρ) ]. The variance is a function of the number of paired samples in the sets being correlated and is defined as var(z) = 1 / (n – 8/3).

Thus, for example, the 95% confidence interval around a correlation estimate would be from (z – 1.96 σ) to (z + 1.96 σ) where σ = sqrt( 1/ (n – 8/3) ).

The iPad version allows you to add, retrieve, reorder, or delete data sets. Also, you may email, send via texting, and print data and results.


## Version history (last 5 releases)

### 8.1 — 2022-04-23

- Corrected colors in Dark mode.
- Fixed problem that prevented sharing of PDF output.
- Various GUI tweaks.

### 8.0 — 2022-02-04

- Update to accommodate latest versions of iOS.
- Some code simplifications.
- Removed links to Facebook and Twitter.
- Various GUI tweaks.

### 7.3 — 2018-12-20

- Updates to newer versions of iOS.
- Various code changes.

### 7.2 — 2015-10-01

- Changes to adapt to iOS 9, mostly involving fonts.

### 7.1 — 2015-07-10

- Bug fixes in iPhone version related to +/– correlation coefficient data entry and clearing of data.
- Added Facebook and Twitter links.
- Code improvements.
- GUI changes.
- Added continuous increase or decrease in confidence interval setting in iPad version.

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All apps by MSYapps: https://appshunter.io/developer/458482419

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-05-19.*