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From |
john metcalfe <johnzmetcalfe@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re: Coding Question |

Date |
Sun, 14 Aug 2011 21:40:49 +0200 |

Thank you very much. John On 8/14/11, Phil Schumm <pschumm@uchicago.edu> wrote: > On Aug 14, 2011, at 11:22 AM, Steven Samuels wrote: >> Even shorter: > > <snip> > >> 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 >> preserve >> collapse (sum) n_convert=convert n_revert=revert, by(id) >> gen both = n_convert*n_revert >0 >> list id n_convert n_revert both >> restore > > > You definitely want the data in long form here, but note that the code above > will fail to capture a switch if it spans a missing value (e.g., 0 -> . -> > 1). Here is an alternative that does not have this limitation: > > reshape long meas, i(id) j(order) > drop if mi(meas) > ass inlist(meas,0,1) > isid id order, so > egen conversion = max(meas>meas[_n-1] & id==id[_n-1]), by(id) > egen reversion = max(meas<meas[_n-1] & id==id[_n-1]), by(id) > gen byte both = conversion & reversion > > > -- Phil > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Coding Question***From:*john metcalfe <johnzmetcalfe@gmail.com>

**st: Re: Coding Question***From:*"Joseph Coveney" <jcoveney@bigplanet.com>

**Re: st: Re: Coding Question***From:*Steven Samuels <sjsamuels@gmail.com>

**Re: st: Re: Coding Question***From:*Phil Schumm <pschumm@uchicago.edu>

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