Previous Page | Next Page

Functions and CALL Routines

CINV Function



Returns a quantile from the chi-square distribution.
Category: Quantile

Syntax
Arguments
Details
Examples
See Also

Syntax

CINV (p,df<,nc>)


Arguments

p

is a numeric probability.

Range: 0 [le] p < 1
df

is a numeric degrees of freedom parameter.

Range: df > 0
nc

is a numeric noncentrality parameter.

Range: nc [ge] 0

Details

The CINV function returns the pth quantile from the chi-square distribution with degrees of freedom df and a noncentrality parameter nc. The probability that an observation from a chi-square distribution is less than or equal to the returned quantile is p. This function accepts a noninteger degrees of freedom parameter df.

If the optional parameter nc is not specified or has the value 0, the quantile from the central chi-square distribution is returned. The noncentrality parameter nc is defined such that if X is a normal random variable with mean [mu] and variance 1, X2 has a noncentral chi-square distribution with df=1 and nc = [mu]2.

CAUTION:
For large values of nc, the algorithm could fail. In that case, a missing value is returned.   [cautionend]

Note:   CINV is the inverse of the PROBCHI function.  [cautionend]


Examples

The first statement following shows how to find the 95th percentile from a central chi-square distribution with 3 degrees of freedom. The second statement shows how to find the 95th percentile from a noncentral chi-square distribution with 3.5 degrees of freedom and a noncentrality parameter equal to 4.5.

SAS Statements Results
q1=cinv(.95,3);
7.8147279033
a2=cinv(.95,3.5,4.5);
7.504582117


See Also

Functions:

QUANTILE Function

Previous Page | Next Page | Top of Page