# Lifetime Evaluation vs. Measurement. Part 3.

Sometimes shifting your perspective

is more powerful than being smart.—Astro Teller

## Guest post by Oleg Ivanov

A common approach for “no failure” testing is the use of the well-known expression

$latex \displaystyle&s=2 (1) \quad 1-CL={{R}^{n}}$

where *CL* is a confidence level, *R* is a required reliability, *n* is a sample size. Its parent is a Binomial distribution with zero failures. This expression is like a poor girl: Continue reading “Lifetime Evaluation vs Measurement Part 3”