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help for ^bsmplot^
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Binomial smoothing plot                                  [STB35:  gr22]
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    ^bsmplot^ yvar xvar [^if^ exp] [^in^ range] [, ^w^indow^(^#^)^ graph_options ]

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

^bsmplot^ produces a scatter plot of yvar and yvar smoothed by a
binomial filter against xvar. Normally, but not necessarily, xvar will
contain equally-spaced times and yvar some fluctuating response.

Binomial filters have weights given by the coefficients in the
                    n
expansion of (a + b) . Thus

       2              2           2
(a + b)  expands to 1a  + 2ab + 1b ,

       4              4     3      2 2      3     4
(a + b)  expands to 1a  + 4a b + 6a b  + 4ab  + 1b ,

and more compactly (listing here only examples with odd numbers of
weights, which are the practical choices in smoothing)

           1  2  1                          length 3
           1  4  6  4  1                    length 5
           1  6 15 20 15  6  1              length 7
           1  8 28 56 70 56 28  8 1         length 9

and so forth. Each weight is divided by the sum of the weights to produce
scaled weights that have sum 1. Thus smoothing with weights in the ratio
1:2:1 means compute smooth at i by

  1/4 value at i-1  +  1/2 value at i  +  1/4 value at i+1,

each weight being divided by the sum 4.

Options
-------

^window(^#^)^ specifies the length of the binomial filter. The default
    is 3, giving the filter with weights in the ratio 1:2:1, often known as
    Hanning. The length must be an odd number and at least 3.

graph_options are options allowed with ^graph, twoway^. The default
    values include

    ^xla yla c(||s) sy(iii) gap(6)^

    ^t1title^ shows the window length

^c(..s)^ would show just the smooth values, suppressing the data.

Examples
--------

        . ^bsmplot temp year^
        . ^bsmplot temp year, w(9)^
        . ^bsmplot temp year, w(9) c(..s)^

Author
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         Nicholas J. Cox, University of Durham, U.K.
         n.j.cox@@durham.ac.uk

Also see
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    STB: gr22 (STB-35)
On-line: help for @smooth@, @graph@, @ksm@