Dapatkan PDF atau CDF dari distribusi gamma
=GAMMA.DIST(x, alpha, beta, cumulative)| Parameter | Deskripsi |
|---|---|
x |
The value at which to evaluate the distribution. |
alpha |
The shape parameter of the distribution. |
beta |
The scale parameter of the distribution. |
cumulative |
A logical value that determines the form of the function. If TRUE, returns the cumulative distribution function; if FALSE, returns the probability density function. |
To calculate the chance of waiting ≤ x hours for the 20th customer, we calculate the probability like this:
=GAMMA.DIST(x, 20, 0.1, TRUE)To calculate the chance of waiting > x hours for the 20th customer:
=1-GAMMA.DIST(x, 20, 0.1, TRUE)For example, to find the probability that the 20th customer arrives in 2 hours or less, use:
=GAMMA.DIST(2, 20, 0.1, TRUE) // 53% chance of waiting ≤ 2 hoursIn this example, we'll calculate the PDF for a gamma distribution with a shape (alpha) of 3 and a scale (beta) of 0.2. The formula is:
=GAMMA.DIST(x, 3, 0.2, FALSE)The peak of the distribution (the mode) can be found with (alpha - 1) * beta, which is (3 - 1) * 0.2 = 0.4. We can calculate the PDF at this peak, and
=GAMMA.DIST(0.4, 3, 0.2, FALSE) // returns 1.353, the peak likelihood
=GAMMA.DIST(0.2, 3, 0.2, FALSE) // returns 0.981
=GAMMA.DIST(0.8, 3, 0.2, FALSE) // returns 0.903Setting the cumulative argument to TRUE returns the cumulative distribution function (CDF), which gives the probability of a random variable being les
=GAMMA.DIST(0.7, 3, 0.2, TRUE) // returns 0.679