help genicv
-------------------------------------------------------------------------------

Title

     genicv -- Generate interaction between continuous (or dummy) variables

Syntax

        genicv varlist [if] [in] [, options]

    options                Description
    -------------------------------------------------------------------------
      replace              replace existing variables
      x(chars)             use chars as separator in variable labels
      sepvars(chars)       use chars as separator for variable names
      mvc(mvc)             replace interactions with mvc if variables have
                             hard missings
      local(macname)       save created variable names in macname
 
    -------------------------------------------------------------------------

Description

    genicv multiplies variables to create two or three-way interactions. If
    two variables are specified in varlist, one new variable
    varname1_varname2 is created as the product of var1 and var2. If three
    variables are specified, genicv creates varname1_varname2_varname3 and
    all three two-way interactions (varname1_varname2, varname1_varname3,
    varname2_varname3). If all variables in varlist are labeled, new variable
    labels will be "labeli * labelj [* labelk]". If one or more variables in
    varlist are not labeled, new variables will not be labeled.

Options

        +---------+
    ----+ options +----------------------------------------------------------

    replace replaces existing variables. Default is to only create variables,
        that do not yet exist.

    sepvars(chars) use varnameicharsvarnamej [charsvarnamek] as variable
        names. Default is "_".

    x(chars) use labeli chars labelj [chars labelk] as variable labels.
        Default is "*".

    mvc(mvc) replaces interactions with hard missing mvc (where mvc is one of
        .a, ..., .z), if one of the original variables has hard missings.

    local(macname) saves the created variable names in r(macname). Default
        macname is icv.


Example

        . sysuse nlsw88 ,clear
        (NLSW, 1988 extract)

        . genicv wage age married

        . describe

        [...]
        -----------------------------------------------------------------------
> -----
                        [...] value
        variable name   [...] label     variable label
        -----------------------------------------------------------------------
> -----
                [...]
        age                             age in current year
                [...]
        married               marlbl    married
                [...]
        wage                            hourly wage
                [...]
        wage_age                        hourly wage * age in current year
        wage_married                    hourly wage * married
        age_married                     age in current year * married
        wage_age_marr~d                 hourly wage * age in current year * mar
> ried
        -----------------------------------------------------------------------
> -----


Saved results

    genicv saves the following in r():

    Macros
      r(macname)           created variable names


Author

    Daniel Klein, University of Bamberg, klein.daniel.81@gmail.com

Also see

    Online: generate, xi, fvvarlist
    if installed: tuples, selectvars, chm