Returns the beta distribution for the specified parameters.

## Syntax

• 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
1. Create a blank workbook or worksheet.
2. Select the example in the Help topic.

Note  Do not select the row or column headers.

Selecting an example from Help

3. Press CTRL+C.
4. In the worksheet, select cell A1, and press CTRL+V.
5. 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