04-28-2017 11:40 AM
In 90% confidence interval for 12 number of degrees of freedom , using Chi-square_(0.90)=5.226 and Chi-square_(0.05)=21.026 while in 95% confidence interval for 19 number of degrees of freedom we using Chi-suqare_(0.975)=8.907 and Chi-square_(0.025)=32.852.
How can selcet a Chi-square interval for given number of degrees of freedom of a confidence level? Hope question is understandable.
04-28-2017 11:52 AM
This will show how to the values for the 5th and 95th percentiles for a Chi-sq with 12 df which would be the boundaries of a symetric 90% interval.
Data example; lower=quantile('CHISQ',.05,12); upper=quantile('CHISQ',.95,12); run;
Request the appropriate quantile as needed. The parameters could be variables in a data set.
04-28-2017 11:54 AM
Actually, the question isn't particularly clear.
You can select a chi-squared confidence interval from any textbook that has a table of the Chi-Squared distribution; and in SAS you can use the CINV function.