A level C confidence interval for μ (Normal case: known σ)
The level C is a value that the experimenter chooses to indicate the level of accuracy desired in the interval estimate. z* is called the critical value. Its value is determined from the standard normal distribution for the specified level of C.
Confidence level C |
z* |
90% |
1.645 |
95% |
1.96 |
99% |
2.575 |