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# Re: st: Re: Coding Question

 From Steven Samuels To statalist@hsphsun2.harvard.edu Subject Re: st: Re: Coding Question Date Sun, 14 Aug 2011 11:56:31 -0400

```John Metcalfe wrote:

I have a matrix of serial measurements with some missing values as
below. I would like to write a simple code that counted each
individual as a 'conversion' (going from 0 to 1), a reversion (going
from 1 to 0), or both. Any ideas appreciated.

Here's an approach using -reshape-.  I've shortened Joseph's names for easier typing.

Steve

*************CODE BEGINS*************
clear
input str8 lid meas1 meas2 ///
meas3 meas4 meas5
"11020189" 0         1         0         1         .
"11030107" 0         1         1         1         .
"11030206" 1         1         1         .         .
"11030207" 0         0         0         .         .
"11030265" 1         1         0         0         0
"11040003" 0         1         1         1         .
"11040079" 1         0         1         0         .
"11040225" 1         0         0         .         .
"11050079" 0         1         1         1         .
"11050203" 1         0         1         1         .
"11060278" 1         0         1         0         .
"11070069" 1         0         0         .         .
"11070195" 1         0         0         0         .
"11070229" 0         1         0         1         .
"11070245" 1         0         0         0         .
end
gen id = _n
reshape long meas, i(id) j(order)
bys id: gen convert = meas ==1 & meas[_n-1]==0
bys id: gen revert = meas == 0 & meas[_n-1] ==1
egen n_convert = total(convert), by(id)
egen n_revert = total(revert), by(id)

preserve
bys id: keep if _n==1
gen both = n_convert*n_revert >0
list id n_convert n_revert both
**************CODE ENDS**************

> On Aug 14, 2011, at 10:15 AM, Joseph Coveney wrote:
>
> --------------------------------------------------------------------------------
>
> Something like that below would work.  I'm assuming that rows are individuals
> and columns are serial measurements.  (You didn't describe or show your variable
> names.)
>
> Joseph Coveney
>
> input str8 individual_id serial_measurement1 serial_measurement2 ///
>    serial_measurement3 serial_measurement4 serial_measurement5
> "11020189" 0         1         0         1         .
> "11030107" 0         1         1         1         .
> "11030206" 1         1         1         .         .
> "11030207" 0         0         0         .         .
> "11030265" 1         1         0         0         0
> "11040003" 0         1         1         1         .
> "11040079" 1         0         1         0         .
> "11040225" 1         0         0         .         .
> "11050079" 0         1         1         1         .
> "11050203" 1         0         1         1         .
> "11060278" 1         0         1         0         .
> "11070069" 1         0         0         .         .
> "11070195" 1         0         0         0         .
> "11070229" 0         1         0         1         .
> "11070245" 1         0         0         0         .
> end
>
> local deltas
> forvalues interval = 2/5 {
>    generate int delta`interval' = ///
>        serial_measurement`interval' - ///
>        serial_measurement`=`interval'-1'
> 	replace delta`interval' = 0 if missing(delta`interval')
> 	local deltas `deltas' delta`interval'
> }
> local deltas : subinstr local deltas " " ", ", all
> generate int conversion = max(`deltas')
> replace conversion = 0 < conversion
> generate int reversion = min(`deltas')
> replace reversion = reversion < 0
> generate byte both = conversion * reversion
> local line_size `c(linesize)'
> set linesize 200
> list, noobs separator(0) abbreviate(20)
> set linesize `line_size'
> exit
>
>

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