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help for ^lexis^                                               (STB-27: ssa7)
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Subdivision of follow-up by time bands
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    ^lexis^ timein fail fup^,^ ^br^eaks^(^x1^,^x2^,^...^,^xk^)^ ^gen^erate^(^varname^)^
                        [ ^up^date^(^varlist^)^ ]


Description
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^lexis^ expands a set of records concerning subjects in a follow-up study into a
larger number of person-time records.  Each record in the new dataset concerns
the follow-up of one subject through one band of a time scale.  Expansion by
several time scales may be achieved by repeated calls to ^lexis^.

The variable ^timein^ contains the entry time for the time scale on which the
observations are being expanded.  The variable ^fail^ contains the outcome at
exit, with failure coded ^1^ and censoring coded ^0^. The variable ^fup^ contains
the observation times.


Options
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^breaks(^x1^,^x2^,^...^,^xk^)^ specifies the breaks for the time bands, in ascending
    order.

^generate(^varname^)^ specifies a new variable to hold the time bands.  This
    variable is coded using the left-hand ends of the bands defined by ^breaks^.

^update(^varlist^)^ specifies variables that contain entry times on alternative
    time scales. These variables are incremented appropriately, allowing
    further expansion in subsequent calls.


Examples
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 . ^lexis agein d y, gen(ageband) br(40,50,60,70)^
 . ^lexis agein d y, gen(ageband) br(40,50,60,70) up(datein)^ 
 . ^lexis datein d y, gen(period) br(1960,1970,1980,1990) up(agein)^


Authors
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        David Clayton, MRC Biostatistical Research Unit, Cambridge
        david.clayton@@mrc-bsu.cam.ac.uk
        Michael Hills, London School of Hygiene and Tropical Medicine, London
        mhills@@lshtm.ac.uk


Also see
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    STB:  STB-27 ssa7
On-line:  help for @mhrate@ and @tabrate@