4 life distributions

Weibull Distribution

x It's a random variable
k＞0 It's a shape parameter （shape parameter）
λ＞0 It's a scale parameter （scale parameter）

When k=1, It's an exponential distribution ;k=2 when , yes Rayleigh distribution( Rayleigh distribution ).

Weibull Distribution
python Draw weibull curve
weibull Parameter estimation

An index distribution

Poisson distribution and exponential distribution continuity Relationship
The time interval between two sales of steamed bread is greater than t Probability
( Equivalent to t The probability of not selling a steamed bun within a certain period of time , The probability of the latter can be determined by Poisson process give )

An index distribution ： Integral process
mean value
variance

$\cdot$ Poisson distribution discrete

E(X)=$\lambda$ \quad D(X)=$\lambda$
$\cdot$ Poisson process

Normal distribution

Lognormal distribution

appendix ：

$\cdot$ Some cumulative distribution functions

$\cdot$12 A common probability distribution

$\cdot$8 The mean and variance of three commonly used probability distributions