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WEIBULL
Returns the Weibull distribution. Use this distribution in reliability analysis, such as calculating a device's mean time to failure.
Syntax
WEIBULL(x,alpha,beta,cumulative)
X is the value at which to evaluate the function.
Alpha is a parameter to the distribution.
Beta is a parameter to the distribution.
Cumulative determines the form of the function.
Remarks
- If x, alpha, or beta is nonnumeric, WEIBULL returns the #VALUE! error value.
- If x < 0, WEIBULL returns the #NUM! error value.
- If alpha ≤ 0 or if beta ≤ 0, WEIBULL returns the #NUM! error value.
- The equation for the Weibull cumulative distribution function is:
- The equation for the Weibull probability density function is:
- When alpha = 1, WEIBULL returns the exponential distribution with:
Example
The example may be easier to understand if you copy it to a blank spreadsheet.
How?
- Create a blank spreadsheet.
- Select the example in the Help topic.
Selecting an example from Help
- Press CTRL+C.
- In the spreadsheet, select cell A1, and press CTRL+V.
- To switch between viewing the formula that returns the result and the result in the cell, select the cell and press F2 and then ENTER, or click Commands and Options on the spreadsheet toolbar, click the Formula tab, and look in the Formula in active cell (active cell) box.
| Data | Description |
|---|---|
| 105 | Value at which to evaluate the function |
| 20 | Alpha parameter to the distribution |
| 100 | Beta parameter to the distribution |
| Formula | Description (Result) |
| =WEIBULL(A2,A3,A4,TRUE) | Weibull cumulative distribution function for the terms above (0.929581) |
| =WEIBULL(A2,A3,A4,FALSE) | Weibull probability density function for the terms above (0.035589) |