Mean and standard deviation
Smallest extreme value
- Mean
- μ – cσ
- Standard deviation
-
Weibull
- Mean
-
- Standard deviation
-
3-parameter Weibull
- Mean
-
- Standard deviation
-
Exponential
- Mean
- θ
- Standard deviation
- θ
2-parameter exponential
- Mean
- θ + λ
- Standard deviation
- θ
Normal
- Mean
- μ
- Standard deviation
- σ
Lognormal
- Mean
-
- Standard deviation
-
3-parameter lognormal
- Mean
-
- Standard deviation
-
Logistic
- Mean
- μ
- Standard deviation
-
Loglogistic
- Mean
-
- Standard deviation
-
3-parameter loglogistic
- Mean
-
- Standard deviation
-
Notation
| Term | Description |
|---|---|
| c | Euler's constant approximately equal to 0.5772 |
| Γ | gamma function |
| μ | location parameter |
| β | shape parameter |
| σ | scale parameter |
| α | scale parameter (Weibull and 3-parameter Weibull) |
| θ | scale parameter (exponential and 2-parameter exponential) |
| λ | threshold parameter |
Median
The 50th percentile. For more information, see the "Percentiles" topic.
Quartiles and interquartile range
First quartile (Q1) = the 25th percentile
Third quartile (Q3) = the 75th percentile
Interquartile range (IQR) = Q3 - Q1
For more information, see the "Percentiles" topic.
