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From |
"Clive Nicholas" <clivelists@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: re: working with panel data with time gaps |

Date |
Sun, 2 Mar 2008 11:39:04 +0000 |

Shantanu Nundy wrote: > I am working with panel data and am struggling to do manipulations with the data given that the time differences between ob[n] and ob[n-1] are not constant.Here is my specific problem at hand: I have a variable that is either 1 or 0. I want to define an "episode" of 1, where episode is defined the time between the first 1 and the last 1 that is followed by at least three 0s AND over at least 21 days. From my list of 1s and 0s, I would to define a "episode_start" variable that is 1 for the start of each episode and for a second variable "episode_day" to be 1 for all days of an episode. The trouble is that in some cases the three 0s may be over 5 days and other times over 25 days. If the three 0s are over 5 days, we need to checking more observations as long as the variable remains 0 until 21 days has been reached.I have found a solution but it is by no means elegant and consists of over 20 lines of the following (where codigo is my panel variable, giardia is the 1 or 0 vari ab! > le, giardia_i is the desire "episode_start" variable, and date is time):by codigo: replace giardia_i=1 if count_result==1 & giardia==1 & (date - date[_n-4] >= 21 | giardia[_n-4]==.) & giardia[_n-4]!=1by codigo: replace giardia_i=1 if count_result==1 & giardia==1 & (date- date[_n-5] >= 21 | date[_n-5]==.) & giardia[_n-4]!=1 & giardia[_n-5]!=1 The user-written -tsspell-, available from SSC, might be of use here. However, I haven't used this routine, so I can't give you examples of how to use it for your specific problem. -- Clive Nicholas [Please DO NOT mail me personally here, but at <clivenicholas@hotmail.com>. Thanks!] "Courage is going from failure to failure without losing enthusiasm." -- Winston Churchill * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**RE: st: re: working with panel data with time gaps***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**References**:**st: re: working with panel data with time gaps***From:*SHANTANU NUNDY <shantanu@jhmi.edu>

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