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help for kernel programs                                    (STB-26:  snp6.1)
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Kernel density estimation
-------------------------

        kernel_prog varname bandwidth density midpoint

        where kernel_prog is one of: 

                kernel_prog     weight
                -----------     ------
                ^kernsim^         uniform
                ^kerntria^        triangular
                ^kernepa^         Epanechnikov
                ^kernquar^        quartic
                ^kerntriw^        triweight
                ^kerncos^         cosinus
                ^kerngaus^        Gaussian


Description
-----------

Each of these programs calculates the kernel density estimate for the existing
variable ^varname^.  The density is estimated at 50 equally-spaced points that
cover the range of ^varname^.  The ^bandwidth^, a user-specified numeric constant,
specifies the width of the density window around each of the 50 points.  The 
50 estimated densities are stored in the new variable ^density^ and the 50
associated grid points are stored in the new variable ^midpoint^.

These procedures can be regarded both as descriptive histogram smoothers as
well as nonparametric density estimators.  The smoothness of the estimates can
be regulated by changing the bandwidth.  Wide intervals produce smooth
results; narrow intervals result in noiser density estimates.

NOTE: These commands are CPU-intensive and may take a long time to execute.


Example
-------

 . ^kernsim snow 10 density midpoint^
 . ^list midpoint density in 1/50^
 . ^graph density midpoint if _n<=50, c(s) s(p)^

        calculates a kernel density estimate of snowfall using the uniform
        weight function, and lists and graphs the estimate.


Authors
-------

        Isaias H. Salgado-Ugarte, Makoto Shimizu and Toru Taniuchi
        University of Tokyo, Faculty of Agriculture,
        Department of Fisheries, Yayoi 1-1-1, Bunkyo-ku
        Tokyo 113, Japan.
        FAX:    81-3-3812-0529
        EMAIL:  isalgado@@tansei.cc.u-tokyo.ac.jp


Also see
--------

    STB:  STB-26 snp6.1, STB-16 snp6
On-line:  help for @ksm@, @warping@ (if installed)