Weibull distribution in Excel

Weibull Distribution in Excel (WEIBULL.DIST)

Excel Weibull distribution is widely used in statistics to obtain a model for several data sets, the original formula to calculate weibull distribution is very complex but we have an inbuilt function in excel known as Weibull.Dist function which calculates Weibull distribution.

Explanation

We have already learned that Weibull distribution is a continuous probability distribution. And Weibull distribution function in excel of two types:

Weibull Cumulative Distribution Function
Weibull Probability Density Function

The only difference between the two types of Weibull distribution function is the cumulative logical argument,

Weibull Cumulative Distribution Function takes True as a cumulative argument whereas Weibull Probability Density Function takes False as a cumulative argument.

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How to use Weibull Distribution in Excel? (with Examples)

To use Weibull distribution we need to have three values which are X, Alpha, And Beta.

X is a value to the function.
Alpha is a parameter to the function.
Beta is also a parameter to the function.
Cumulative is a logical argument that can be either true or false depending upon the type of Weibull distribution function we are trying to use. If we are using Weibull Cumulative Distribution Function then the cumulative value will be true or we are using Weibull Probability Density Function then the cumulative value will be false.

You can download this Weibull Distribution Excel Template here – Weibull Distribution Excel Template

Example #1

AS we know X is valued at which we evaluate the function, Alpha & Beta both are the parameters to the function. Let us use this function in excel.

Step#1 – Give value to the WEIBULL.DIST function, for example, 100

Step#2 – Now let us give the parameter to the function i.e. Alpha and Beta.

Step#3 – In the Weibull Distribution Box, Type

Step#4 – Press the Tab button and click on the Fx function button.

Step#5 – A dialog box pops up.

Step#6 – In the Box for X select the value against the value to the function.

Step#7 – For the parameter to the function, select the value for alpha and beta,

Step#8 – Cumulative is a logical value that can be either true or false and both have a different meaning. Let us insert true first.

Step#9 – Click on and we get the result for Weibull distribution.

The above value calculate is Weibull Cumulative Distribution. To get this the value of cumulative should be true.

Example #2

We have seen that Inserting True in the value of cumulative gives us Weibull Cumulative Distributive Value. If we insert False at the cumulative it gives us Weibull Probability Density Value. Let us go with the first example.

We have seen that X is valued at which we evaluate the function, Alpha & Beta both are the parameter to the function. Let us again use this function in excel.

Step#1 – We will again give a value to the function, i.e. 190 for this case.

Step#2 – Now we give a parameter to the function which is alpha and beta,

Step#3 – Now in the Weibull distribution box type,

Step#4 – Press Tab and click on Fx function bar,

Step#5 – A dialog box appears for the function arguments,

Step#6 – Now we will give the value of the function and value of the parameters i.e. Alpha and Beta.

Step#7 – Previously We inserted True as the value in cumulative now we will insert False as a value in the cumulative logical value.

Step#8 – Click on OK and we will get our desired value.

The value above calculated is Weibull Probability Density.

Things to Remember

X which is a value to the function is a non-negative number and cannot be zero, so it should be greater than zero.
Alpha And Beta which are the parameter to the function the also need to be equals to or greater than zero.
We get two types of errors in Excel Weibull Distribution.
#NUM!: This error comes when the value of x is less than zero.
#Value!: This error comes if any arguments given is non-numeric.