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help for datacheck
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Assert with report

        datacheck true_or_false_condition [if condition] [in range] [ ,
                 by(byvarlist) message(string) varshow(varlist) previous next
                 flag nolist list_options ]


Description

    datacheck is a utility that checks for each observation that a specified
    condition is true and reports on any observations for which it is false.


Options

    by(byvarlist) makes the assertion by byvarlist:. This allows, for
        example, conditions referring to _n and _N defined within distinct
        groups of byvarlist.  The dataset must be previously sorted by
        byvarlist. If this option is specified, list output is by default
        separated by byvarlist.

    message(string) displays the given message string if any contradictions
        are found.

    varshow(varlist) restricts list output to the variables in varlist. If
        this option is not specified, all variables in the dataset are
        listed.

    previous and next list the previous and/or following observation as well
        as any observation contradicting the assertion. This can be
        especially useful when data are in time order.

    flag leaves behind a binary flag variable in the dataset named _contra
        taking the value 1 for observations failing the check and 0
        otherwise.  This flag variable will automatically be dropped the next
        time datacheck is run, and a new variable will be generated the next
        time datacheck is run with this option.

    nolist suppresses output of list. Output is restricted to a brief report
        on contradictions.

    list_options are options of list.


Remarks

    Unlike assert, a contradiction of the condition will not produce an
    error, but only output which must be displayed for the contradiction to
    be detected.  Thus always use this command noisily if using run to run do
    files.


Examples

    . datacheck age < ., varshow(id age) message(Missing age)

    . datacheck drug == 3 if arm == 1, varshow(id drug arm) message(Wrong
        drugs)

    . datacheck time > time[_n-1], varshow(id time) message(Dates do not
        follow) prev

    . datacheck time==0 if _n == 1, by(id) varshow(id time) message(Patient's
        first record is not at time 0)


Author

    Krishnan Bhaskaran
    London School of Hygiene and Tropical Medicine
    Keppel Street
    London
    WC1E 7HT
    krishnan.bhaskaran@lshtm.ac.uk


Also see

    Manual:  [D] assert