Methods and formulas for distribution characteristics in Distribution ID Plot (Arbitrary Censoring)

Mean and standard deviation

Smallest extreme value

Mean
μ
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

TermDescription
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.

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