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From |
"Ada Ma" <heu034@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: coding problem: looping through a list of ID's |

Date |
Tue, 25 Nov 2008 13:18:08 +0000 |

how about not using loop? I see that you have an age variable but I have no idea how it looks like (for instance is it all rounded up?) so let's assume that you have a date variable and it is in Stata's date format so that I can count the number of days elapsed in between height being measured. I am also assuming that you don't mind negative height growth. You may be able to tailor my suggestion somehow to fit your purpose. bysort pt_id (date): gen heightgrowth=pt_ht-pt_ht[_n-1] bysort pt_id (date): gen timeelapsed=date-date[_n-1] gen heightgrowthperyear=heightgrowth/timeelapsed*365.25 On Mon, Nov 24, 2008 at 3:23 PM, Leny Mathew <lenymathewc@gmail.com> wrote: > Dear Statalisters, > I've have been using stata for a while but > am a novice when it comes to loops and macros. I'm hoping that someone > on the list could help with with the following problem. I have a data > set with 74 patients each with 148 measurements of height over a > period of 10 years. The height measurements for all cases are not > necessarily at the same time and not everybody has 148 measurements. > The number 148 is a result of changing the data set into the long > form. > I'm trying to calculate the the the increase in height for a one year > (approximately) interval for each case. I developed the following code > for this purpose, but am not able to get it to work perfectly. It > loops though each patient, but at the end, 'phv' end up being the same > for everyone in the data. Also, this code might be a totally > convoluted way of doing this and I'm hoping that someone could give me > some pointers on how to improve/ revamp this completely. > If this posting is a violation of the list protocol on type of > posting, please feel free to let me know and I'll take it off. I've > spent quite some time tweaking this and am out of ideas. > I'm using stata10.1 Any suggestions are much appreciated. > > Note: 'dov' is date of visit, used to create age. > > sort pt_id dov > by pt_id: gen timec=_n > > gen counter=_n > > sort pt_id dov > by pt_id: gen num=_N > > local j=counter > local i=1 > local k=1 > while pt_id <75 { > display pt_id[_n] > while (pt_id[`j']==pt_id[`j'+1]) & timec < 148{ > local value= max(`j'+147, num[pt_id]) > while (`value' > > max(`j',1)) & (`value' > timec[`j']) & (pt_id[`j']==`k') { > replace phv= > (pt_ht[`value']-pt_ht[counter[`i']]) if > ((age[`value']-age[counter[`i']]) >0.95 & > (age[`value']-age[counter[`i']]) < 1.5) & (pt_id[`j']==`k') > local i= `i'+1 > if `i'==`value' local > value= `value'-1 > if `i'==`value'+1 & > pt_id[`j']==1 local i=1 > if `i'==`value'+1 & > (pt_id[`j'] >1) local i=(`k'-1)*148 > } > local i=`i'+148 > local j=`j'+148 > display `j' > local k=`k'+1 > display `k' > continue > if k >74 break > } > } > > > **I tried to use phv[`value'] so that it would replace the value at > the certain row, but that gave me an error that weights are not > allowed. (I'm sure that that must have been a violation of stata > rules!) > > > > > Leny > * > * 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/

**Follow-Ups**:**Re: st: coding problem: looping through a list of ID's***From:*"Leny Mathew" <lenymathewc@gmail.com>

**References**:**st: coding problem: looping through a list of ID's***From:*"Leny Mathew" <lenymathewc@gmail.com>

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