Functions and CALL Routines 
Returns a quantile from the chisquare distribution.

p

is a numeric probability.
Range: 
0 p
< 1 

df

is a numeric degrees of freedom parameter.

nc

is a numeric noncentrality parameter.
Range: 
nc 0 
The CINV function returns the p^{th} quantile from the chisquare
distribution with degrees of freedom df and a
noncentrality parameter nc. The probability that
an observation from a chisquare 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 chisquare
distribution is returned. The noncentrality parameter nc
is defined such that if X is a normal random variable with mean and variance 1, X^{2} has a noncentral
chisquare distribution with df=1 and nc = ^{2}.
 CAUTION:
 For large values of nc,
the algorithm could
fail. In that case, a missing value is returned.
Note: CINV is the inverse of the PROBCHI
function.
The first statement following shows how to find the
95^{th} percentile from a central chisquare distribution
with 3 degrees of freedom. The second statement shows how to find the 95^{th} percentile from a noncentral chisquare 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

Copyright © 2011 by SAS Institute Inc., Cary, NC, USA. All rights reserved.