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help for ^intterms^                            (statalist distribution 27apr1998)
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Generate all indicators for all intersections of two categorical variables
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       ^intterms^ variable1 variable2  [^if^ exp] [^in^ range] , ^gen(^var_stub^)^ 
                  [^, nodrop^ ^full^ ^index^ ]

Description
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^intterms^ generates a set of indicators for all intersections of two
categorical variables.


Required "option"
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^gen(^var_stub^)^ designates the "variable stub" which will be used as the
    leading characters in the indicator variable names.  Note, use only a
    single character if you wish to allow the maximum number of digits for use
    in representing the categories -- 6 digits.

Options
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^nodrop^ indicates that the first indicator variable *NOT* be dropped from
    the set of generated variables.  This option creates a set of indicators
    that fully span the space and are collectively collinear.

^full^ indicates that indicators should be generated for all combinations of
    the two variables, even if the indicator is constant for a combination.

^index^ specifies that the "index" values of the categories be used in naming
    the indicator variable rather than the values of the variable.  For
    example, if ^cat1^ takes on the values 1, 2, 5, 6 and "D" were specified
    on the ^gen()^ option; the indicator variables would normally start
    with D1... , D2..., D3...., D5...., D6.... .  With the ^index^ option,
    the indicators would be named D1... , D2..., D3...., D4...., D5.... .

Examples
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    . intterms mpg foreign, gen(D)
    . intterms mpg foreign, gen(ivar) index


Author
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     Vince Wiggins
     StataCorp.
     vwiggins@@stata.com

Also see
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 Manual:  ^[U] 26 Estimation and post-estimation commands^
          ^[U] 35 Overview of model estimation^
          ^[R] xi^
On-line:  ^[R] xi^,  help for any estimation command
