Some problems about ttest and esccr functions.

From: Xuguang Sun (sunxg007 AT XXXXXX)
Date: Sun Apr 13 2003 - 06:34:00 MDT

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    Hi, Everyone,
      
     As for ttest, when two original samples are assumed
    to have the same population variance, the parameter
    iflag is set to True in ttest function in NCL, and
    subroutine ttest.for is used in Numeric Recipi,
    whereas the two original samples are assumed to have
    the different population variance, the parameter iflag
    is set to False in ttest function in NCL, and
    subroutine tutest.for is used in Numeric Recipi. But
    actually, when I compared the results of ttest in NCL
    and NR, I found the results in NCL and NR just
    corresponded across, so I guess there is something
    wrong with ttest function in NCL.

    As for correlation function, suppose there are two
    samples x and y, when I calculated the correlation of
    x leading y, I did it in NCL like
    x_lead_y=esccr(y,x,maxlag), but actually, I found the
    result was not I wanted, it was y leading x
    correlation, I have compared the result in NCL with
    other results that I made with fortran and GrADS, so I
    guess there is also something wrong with esccr
    function in NCL.

    I hope someone can do something confirming my guess,
    and then give feedbacks to NCL workshops.

    =====
    SUN Xuguang
    Department of Atmospheric Sciences
    Nanjing University
    Nanjing 210093
    P.R.China

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