Confidence Interval

In statistics, confidence intervals can be used to express the degree to which sample results are reliable.

Confidence intervals are often stated in terms of a percentage like 90% or 95%. When the sample or population distribution is the Normal (bell-shaped) distribution, the confidence intervals can be represented as a number of standard deviations (σ) above or below the sample mean (μ).

Moving the slider beneath the graph will vary the confidence intervals from 50% to 99%. Additionally, you may choose the two-tailed confidence intervals or the one-tailed interval by tapping the button beneath the slider.

In this application, you may chose the standardized Normal distribution with μ=0.0 and σ=1.0 or some other values for mean and standard deviation.


change in version 2.2
  • Updated to iOS8
  • GUI changes
change in version 2.0
  • Major rewrite and redesign for iOS 7
changes in version 1.5
  • Minor GUI enhancements
  • Updated the graphing engine
changes in version 1.3
  • Expanded screens to accommodate size of iPhone 5
  • Bug fixes
changes in version 1.2
  • Fixed bug in data entry routine
  • Improved precision from single to double
  • Modified syntax of iTunes App Store link

revised: August 7, 2020