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In R software, we compute an empirical cumulative distribution function, with several methods for plotting, printing and computing with such an “ecdf” object. In MATLAB we can use Empirical cumulative distribution function (cdf) plot; jmp from SAS, the CDF plot creates a plot of the empirical cumulative distribution function.
Cumulative distribution function for the exponential distribution Cumulative distribution function for the normal distribution. In probability theory and statistics, the cumulative distribution function (CDF) of a real-valued random variable, or just distribution function of , evaluated at , is the probability that will take a value less than or equal to .
The inverse cumulative distribution function (quantile function) of the logistic distribution is a generalization of the logit function. Its derivative is called the quantile density function. They are defined as follows: (;,) = + ().
Weibull plot. The fit of a Weibull distribution to data can be visually assessed using a Weibull plot. [17] The Weibull plot is a plot of the empirical cumulative distribution function ^ of data on special axes in a type of Q–Q plot.
The complement of the standard normal cumulative distribution function, () = (), is often called the Q-function, especially in engineering texts. [ 13 ] [ 14 ] It gives the probability that the value of a standard normal random variable X {\displaystyle X} will exceed x {\displaystyle x} : P ( X > x ) {\displaystyle P(X>x
Because of the factorial function in the denominator of the PDF and CDF, the Erlang distribution is only defined when the parameter k is a positive integer. In fact, this distribution is sometimes called the Erlang- k distribution (e.g., an Erlang-2 distribution is an Erlang distribution with k = 2 {\displaystyle k=2} ).
When c = 1, the Burr distribution becomes the Lomax distribution.; When k = 1, the Burr distribution is a log-logistic distribution sometimes referred to as the Fisk distribution, a special case of the Champernowne distribution.
In probability theory, a log-normal (or lognormal) distribution is a continuous probability distribution of a random variable whose logarithm is normally distributed.Thus, if the random variable X is log-normally distributed, then Y = ln(X) has a normal distribution.