Dave Goel <[EMAIL PROTECTED]> writes:
> Consider a=[1 2 3 4], and b=[5 6 7 8]. > > The null is a = b. The alt. is !=. > > We get > > octave:3> kolmogorov_smirnov_test_2 (a,b,"!=") > pval: 0.0366311 > > > > Now consider an even more ridiculous null of a>b. In this case, the > alt. is "<", So, p should get even lower. But, > octave:5> kolmogorov_smirnov_test_2 (a,b,"<") > pval: 1 > > > Now, consider a very plausible null of a<b. The alt. is ">". P should > now be about 1, but we get: > > octave:6> kolmogorov_smirnov_test_2 (a,b,">") > pval: 0.0183156 > > > It seems that the meaning of < and > are flipped in the test. Note > that the third argument refers to ALT, and not to NULL, as for > example, seen for the case of !=. > > > > I have tested this with the latest octave as well. I can now report that the exact same problem exists in u_test of octave, and probably more generally, in others as well. (FWIW, I checked matlab's ttest2, and there, the meaning of alt there is correctly interpreted - its results match its documentation for "both", "right" and "left"). - dave ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ Octave-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/octave-dev
