# Minitab Handbook for 95/95 Confidence and Reliability

## Overview

### Confidence and Reliability Explained

You may have seen the numbers thrown around: 90/80 reliability, 95/95 reliability, 95/99 reliability, and 99/99 reliability. In the context of confidence and reliability, the first number is the confidence level, and the second number is the reliability level. So, for example, if a process has achieved 95/95 confidence and reliability, you know that you can be 95% confident that 95% of the units in your population are good.

### Confidence and Reliability in Minitab Statistical Software

Let’s assume you have determined that your risk level is relatively high, so you want to demonstrate 95/99 confidence and reliability. It turns out that there are many ways to do this, and the best approach depends on a few practical and statistical considerations.

Let’s start by using the flowchart below to determine which of the tools in Minitab Statistical Software will work best for demonstrating 95/99 or another confidence and reliability goal given your specific situation.

Basic statistics courses usually teach sampling in the context of surveys: you administer the survey to a representative sample of individuals, then extrapolate from that sample to determine whether certain effects are statistically significant. We hear the results of such sampling every day in the news.

The idea behind these methods is similar: we inspect or test a representative sample of units, then extrapolate from that sample to make an inference about the reliability of the entire population we sampled from.