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help for missingplot 
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A plot to show patterns of missing values in a dataset

        missingplot [varlist] [if exp] [in range] [, all labels variablenames
                 scatter_options]


Description

    missingplot gives a plot showing the incidence of missing values in one
    or more variables in the current dataset. The horizontal axis shows
    observation numbers; the vertical axis shows one or more lines, one for
    each variable shown. Marker symbols show which values are missing.

    missingplot treats numeric and string variables alike: what is common to
    both is whether the missing() function returns true. In the case of
    numeric variables no distinction is made between system missing (.) and
    any extended missing value .a ... .z. See missing for a tutorial if
    desired.  Users wishing to select classes of variables, for example all
    numeric or all string variables, may wish to use first either ds or 
    findname (if installed).

    missingplot may be useful for seeing broad patterns in the incidence of
    missing values, for example blocks of observations with many or all
    missing values or variables with many or all missing values.  It may also
    be useful for quickly identifying fine structure or notable detail in
    some instances. See also misstable (Stata 11 up) and nmissing (if
    installed).


Remarks 

    For a loosely similar plot, see Wilkinson (2005, p.487). Users of this
    program knowing of references to interesting earlier or similar work are
    encouraged to send references to the program author.

    The mechanics of the plot are that each variable in the plot is
    represented by a single variable inside the program. There is currently a
    limit of 20 variables being shown in any one graph.


Options

    all specifies that all variables implied by varlist should be plotted,
        regardless of whether they contain missing values.  The default of
        missingplot is to omit variables from the plot if they have no
        missing values (in the observations selected, if either if or in has
        been specified). Specifying all is more likely to trigger the limit
        of 20 variables shown.

    labels specifies that marker labels be shown identifying the observation
        number of each missing value. In practice this will work best with a
        small number of missing values or a small dataset or both.  Note that
        as above marker labels are generated by repeated calls to marker
        label options for each variable; thus if you wish to change away from
        the default you would need to specify (e.g.) mlabcolor(blue ..).

    variablenames specifies that variable names only be shown to identify
        variables. The default is to show variable labels if they exist, and
        variable names otherwise. The value of this option is usually to
        increase the space devoted to the graph itself.

    scatter_options are options of scatter.


Examples

    . webuse nlsw88, clear
    . missingplot
    . missingplot, var labels
    . missingplot, var labels mlabcolor(blue ..)


Author 

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


References 

    Cox, N.J. 1999. Numbers of missing and present values.  Stata Technical
        Bulletin 49: 7-8.  (Software updates Stata Technical Bulletin 60:
        2-3; Stata Journal 3:449 and 5:607)

    Cox, N.J. 2010. Finding variables. Stata Journal 10: 281-296.  (Software
        updates Stata Journal 10:691 and 12:167)

    Wilkinson, L. 2005. The Language of Graphics. New York: Springer.


Also see