Manuals/calci/BETAINV

BETAINV(prob,alpha,beta,a,b)

• $prob$ is the probability value associated with the beta distribution.
• $alpha$ & $beta$ are the values of the shape parameter.
• $a$ & $b$ the lower and upper limit to the interval of $x$.

Description

• This function gives the inverse value of Cumulative Beta Probability Distribution.
• It is called Inverted Beta Function or Beta Prime.
• In $BETAINV(prob,alpha,beta,a,b)$, $prob$ is the probability value associated with Beta Distribution, $alpha$ and $beta$ are the values of two positive shape parameters and $a$ and $b$ are the lower and upper limit.
• Normally the limit values are optional, i.e. when we are giving the values of $a$&$b$ then the result value is from $a$ and $b$.
• When we are omitting the values $a$ and $b$, by default it will consider $a=0$ and $b=1$, so the result value is from $0$ and $1$.
• If $BETADIST(x,alpha,beta,a,b)=prob$, then $BETAINV(prob,alpha,beta,a,b)=x$.
• $BETAINV$ use the iterating method to find the value of $x$.suppose the iteration has not converged after 100 searches, then the function gives the error result.
• This function will give the error result when

1.Any one of the arguments are non-numeric
2.$\alpha$ or $\beta \leq 0$
3.$x<a,x>b$ or a = b
4.we are not mentioning the limit values  for $a$&$b$, 
  by default it will consider the Standard Cumulative Beta Distribution, a = 0 and b = 1

ZOS

• The syntax is to calculate of this function in ZOS is $BETAINV(Probability,Alpha,Beta,LowerBound,UpperBound,Accuracy)$.
  • $probability$ is the probability value associated with the beta distribution.
  • $alpha$ and $beta$ are the values of the shape parameter.
  • For e.g.,BETAINV(0.30987,10,18,12,16)

Examples

1. BETAINV(0.2060381025,5,9,2,6) = 3
2. BETAINV(0.359492343,8,10) = 1.75
3. BETAINV(0.685470581,5,8,2,6) = 3.75
4. BETAINV(0.75267,1,7,7,9) = 7.25
5. BETAINV(0.5689,-2,4,3,5) = NAN, because $\alpha <0$.

See Also

• BETADIST
• All Functions

References

Beta Distribution