help labmv
-------------------------------------------------------------------------------

Title

     labmv -- Change numeric values to extended missing values preserving value
labels


Syntax

        labmv [varlist] [if] [in] , mv(numlist | # [mvc] ...) [options]


     where mvc is one of the extended missing value codes .a|.b|...|.z


Description

    labmv changes numeric values in a specified varlist to extended missing
    values, preserving their value labels. If no mvc is specified, numeric
    values are changed to consecutive extended missing value codes, starting
    with .a. Thus, the first numeric value specified will be coded .a, the
    second .b and so on.  In value labels, any text associated with numeric
    values will be detached from these values and instead be associated with
    the corresponding missing value code.

    Up to 26 numeric values may be specified in mv. If varlist is not
    specified it defaults to _all.

    Reminder: modifiactions in value labels affect all variables that have
    the same value label as one of the variables in varlist attached.


Options

    mv(numlist | # [mvc]) is a required option and specifies numeric values
        to be changed to extended missing value codes. The numeric value
        preceding mvc is changed to mvc.  See Remarks.

    allvars changes numeric values to extended missing values in all
        variables that have the same value label as one of the variables in
        varlist attached.

    nodelete prevents labmv from deleting value labels that are changed. If
        specified numeric missing values and extended missing value codes
        will be associated with the same text.

    fmvc(mvc) specifies the first extended missing value code to be used.
        Default is .a. Note that the maximum number of values allowed in mv
        is potentially reduced if mvc > .a.

    encode changes extended missing value codes to numeric values, preserving
        value labels and, thus, reversing the default behavior. The first
        missing value code (default .a) is changed to the first value
        specified in mv and so on. In mv, mvc is changed to the numeric value
        follwing mvc. See Remarks.

    current changes value labels in the current label language only.


Remarks

    labmv changes one numeric value to one extended missing value code. In

        labmv ,mv(1/3)

    values 1, 2 and 3 are changed to .a, .b and .c respectively. This is the
    same as

        labmv ,mv(1 .a 2 .b 3 .c)

    Specifying mvc changes the numeric value preceding mvc to mvc. In

        labmv ,mv(1/3 .f)

    only value 3 is changed to .f. Values 1 and 2 are changed to .a and .b
    respectively.

    To reverse the above, type

        labmv ,mv(1 2 .f 3) encode

    Option fmvc may be specified if mvc is specified in mv. The line

        labmv ,mv(1/3 .f) fmvc(.y)

    changes values 1 and 2 to .y and .z respectively.  Value 3 is changed to
    .f.

    More confusing specifications are allowed. In

        labmv ,mv(1/3 .f) fmvc(.e)

    values 1 and 2 are changed to .e and .g respectively. Since value 3 is
    followed by .f it is changed to .f.


Example

        . sysuse nlsw88
        . tab1 race married
        . label list racelbl marlbl

    Decode missing values
        . labmv race married ,mv(1 2)
        . tab1 race married
        . tab1 race married ,missing
        . label list racelbl marlbl

    Encode missing values
        . labmv race married ,mv(1 2) encode
        . tab1 race married
        . label list racelbl marlbl


Saved results

    labmv saves the following in r():

    Macros
      r(values)      numeric values
      r(mvc)         extended missing value codes
      r(varlist)     changed variables (if any)
      r(lblnamelist) changed value labels (if any)
      r(k)           number of numeric values
      r(minmvc)      minimum extended missing value code
      r(maxmvc)      maximum extended missing value code
      r(languages)   label languages (multilingual datasets only)


Acknowledgments

    labmv is strongly inspired by nepsmiss (Jan Skopek, Daniel Bela).

    Daniel Possenriede suggested user-defined missing value codes in mv.


Author

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


Also see

    Online: mvdecode, label

    if installed: labelmiss, nepsmiss, labutil2