BETAINV

MS Excel Spreadsheet

See Also

Returns the inverse of the cumulative beta probability density function. That is, if probability = BETADIST(x,...), then BETAINV(probability,...) = x. The cumulative beta distribution can be used in project planning to model probable completion times given an expected completion time and variability.

Syntax

BETAINV(probability,alpha,beta,A,B)

Probability    is a probability associated with the beta distribution.

Alpha    is a parameter to the distribution.

Beta    is a parameter to the distribution.

A    is an optional lower bound to the interval of x.

B    is an optional upper bound to the interval of x.

Remarks

  • If any argument is nonnumeric, BETAINV returns the #VALUE! error value.
  • If alpha ≤ 0 or beta ≤ 0, BETAINV returns the #NUM! error value.
  • If probability ≤ 0 or probability > 1, BETAINV returns the #NUM! error value.
  • If you omit values for A and B, BETAINV uses the standard cumulative beta distribution, so that A = 0 and B = 1.

BETAINV uses an iterative technique for calculating the function. Given a probability value, BETAINV iterates until the result is accurate to within ±3x10-7. If BETAINV does not converge after 100 iterations, the function returns the #N/A error value.

Example

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

ShowHow?

Data Description
0.685470581 Probability associated with the beta distribution
8 Parameter to the distribution
10 Parameter to the distribution
1 Lower bound
3 Upper bound
Formula Description (Result)
=BETAINV(A2,A3,A4,A5,A6) Inverse of the cumulative beta probability density function for the parameters above (2)