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CNONCT |
Category: | Mathematical |
Syntax | |
Arguments | |
Details | |
Examples |
Syntax |
CNONCT(x,df,prob) |
Range: | x 0 |
Range: | df > 0 |
Range: | 0 < prob < 1 |
Details |
The CNONCT function returns the nonnegative noncentrality parameter from a noncentral chi-square distribution whose parameters are x, df, and nc. If prob is greater than the probability from the central chi-square distribution with the parameters x and df, a root to this problem does not exist. In this case a missing value is returned. A Newton-type algorithm is used to find a nonnegative root nc of the equation
where
where is the probability from the gamma distribution given by
If the algorithm fails to converge to a fixed point, a missing value is returned.
Examples |
data work; x=2; df=4; do nc=1 to 3 by .5; prob=probchi(x,df,nc); ncc=cnonct(x,df,prob); output; end; run; proc print; run;
Computations of the Noncentrality Parameters from the Chi-squared Distribution
OBS x df nc prob ncc 1 2 4 1.0 0.18611 1.0 2 2 4 1.5 0.15592 1.5 3 2 4 2.0 0.13048 2.0 4 2 4 2.5 0.10907 2.5 5 2 4 3.0 0.09109 3.0 |
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