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help for tabcond
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Tabulate frequencies satisfying specified conditions

  tabcond groups varname [if exp] [in range] [weight] , cond(condition_list) [
           listwise tabdisp_options ]

  tabcond variables varlist [if exp] [in range] [weight] , cond(condition_list)
           [ listwise tabdisp_options ]

by ... : may be used with tabcond; see by.  fweights, aweights, and iweights
are allowed; see weights.


Description

tabcond tabulates frequencies satisfying up to 5 specified conditions. Zero
frequencies are shown explicitly.

There are two syntaxes. With tabcond groups, the rows of the table show the
distinct groups of varname and the columns show the frequencies of observations
satisfying specified conditions. With tabcond variables, the rows of the table
show the variables specified and the columns show the frequencies of
observations satisfying specified conditions: the conditions must each include
a wildcard @ for which is substituted in turn each variable name.


Options

cond(condition_list) specifies a list of true or false conditions, for which
    the frequencies (zero or more) of observations satisfying those conditions
    are to be shown. Unless they can expressed without embedded spaces,
    conditions must be bound in double quotes " " and if necessary compound
    double quotes `" "'. This is a required option.

listwise specifies that frequencies should be determined for as many
    observations as possible.  By default casewise deletion on varlist is used
    to ensure consistency in observations selected.

tabdisp_options are options of tabdisp, which may be used to tune the
    appearance of the table.

Examples

    . tabcond g rep78, c("mpg > 30" "mpg <= 30" "weight > 3000")

    . tabcond g rep78, c(mpg>30 mpg<=30 weight>3000)

The two commands above have the same result, except that conditions are echoed
exactly as typed as column headings.

    . bysort foreign: tabcond g rep78, c("mpg > 30" "mpg <= 30")

    . tabcond v price-foreign, c("@ < 0")

    . tabcond v *, c(missing(@)) listwise


Author 

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


Acknowledgements 

        Kit Baum made many useful comments on this problem.