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help for epiweek                                                      (Tim Chu)
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Title

    epiweek -- Generating epidemiogical week and epidemiological year


Syntax

    epiweek varname [if] [in] , epiw(newvarw) epiy(newvary)



Description

    epiweek creates epidemiological week and equivalent epidemiological year
    from the calendar date. US CDC and WHO definition the epidemiological
    week as:

        Each epidemiological week begins on a Sunday and ends on Saturday.
        The first epidemiological week of year ends on the first Saturday of
        January, provided that it falls at least four or more days into the
        month.

    It needs to note that calendar date need to assign to "%td" type before
    running the program.


Example

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    Setup
        . webuse dow1

    Create new variables epi_week and epi_year
        . epiweek date, epiw(epi_week) epiy(epi_year)


Author

    Tim Chu
    Public Health Information Analyst
    Vancouver Coastal Health
    Vancouver, Canada
    tim.chu@vch.ca