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NTBETADIST

Returns the beta distribution for the specified parameters.

Syntax

NTBETADIST(

x,
Alpha,
Beta,
Cumulative

)

Parameters

x is the value for which you want the distribution ( $0\leq x\leq 1$ ).
Alpha is a parameter of the distribution $\alpha\;(>0)$ .
Beta is a parameter of the distribution $\beta\;(>0)$ .
Cumulative is a logical value that determines the form of the function. If cumulative is TRUE, NTBETADIST returns the cumulative distribution function; if FALSE, it returns the probability density function.

Remarks

Probability density function is given as:
$f(x)=\frac{x^{\alpha-1}(1-x)^{\beta-1}}{B(\alpha,\beta)}$

, where $B(\cdot,\;\cdot)$ is beta function.
Cumulative distribution function is given as:
$F(x)=I_{x}(\alpha,\;\beta)$

, where $I_x(\cdot,\;\cdot)$ is regualarized incomplete beta function.
When the argument Cumulative=TRUE, this function returns same result as Excel function “BETADIST” does.

Example

The example may be easier to understand if you copy it to a blank worksheet

How to copy an example

Create a blank workbook or worksheet.
Select the example in the Help topic.
Note Do not select the row or column headers.

Selecting an example from Help
Press CTRL+C.
In the worksheet, select cell A1, and press CTRL+V.
To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Tools menu, point to Formula Auditing, and then click Formula Auditing Mode.


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A	B
Data	Description
0.5	Value for which you want the distribution
8	Value of parameter Alpha
2	Value of parameter Beta
Formula	Description (Result)
=NTBETADIST(A2,A3,A4,TRUE)	Cumulative distribution function for the terms above
=NTBETADIST(A2,A3,A4,FALSE)	Probability density function for the terms above

Download sample excel sheet

See also

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