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Re: st: AW: AW: Automating intervals creation


From   Thomas Speidel <thomas@tmbx.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: AW: AW: Automating intervals creation
Date   Tue, 25 Aug 2009 17:25:59 -0400

Thanks Martin.
Let's take this obs, for example:

idnum	wt20	wt30	wt40	wt50	wt60	wt70	weight	age_ref	weightlst
721	102	147					180	39	30

Using the suggested approach:

gen weight_decades = abs(wt20 - wt30) + ... + abs(wt60 - wt70)

will generate a missing value. But even if it was to work, for this
specific case I would need to add to it the interval abs(147 - 180) because
age_ref > weightlst.
I hope this makes it clearer.


On Tue, 25 Aug 2009 23:02:04 +0200, "Martin Weiss" <martin.weiss1@gmx.de>
wrote:
> 
> <>
> 
> I overlooked the missings issue, which -rowtotal- handles more
gracefully,
> sorry about that! 
> 
> 
> 
> " In general, if age_ref > weightlst, I need one more interval computed"
> 
> 
> What should the additional interval contain?
> 
> 
> HTH
> Martin
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Martin Weiss
> Gesendet: Dienstag, 25. August 2009 22:45
> An: statalist@hsphsun2.harvard.edu
> Betreff: st: AW: Automating intervals creation
> 
> 
> <>
> 
> 
> Your
> 
> 
> ***
> gen delta1 = abs(wt20 - wt30)
> gen delta2 = abs(wt30 - wt40)
> gen delta3 = abs(wt40 - wt50)
> gen delta4 = abs(wt50 - wt60)
> gen delta5 = abs(wt60 - wt70)
> egen weight_decades = rowtotal(delta1 delta2 delta3 delta4 delta5)
> ***
> 
> 
> could be easily shortened:
> 
> 
> 
> ******
> clear*
> inp x1 x2 x3
> 1 2 3
> 3 2 5
> 5 9 11
> 2 34 90
> 54 32 9
> end
> 
> //easy
> gen weight_decades = abs(x1 - x2)+abs(x2-x3)
> 
> /difficult
> gen delta1=abs(x1 - x2)
> gen delta2=abs(x2-x3)
> egen weight_decades2 =rowtotal(delta1 delta2)
> 
> //let`s see
> compare weight_decades weight_decades2
> l we*, noo
> ******
> 
> 
> HTH
> Martin
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Thomas
Speidel
> Gesendet: Dienstag, 25. August 2009 22:36
> An: statalist@hsphsun2.harvard.edu
> Betreff: st: Automating intervals creation
> 
> I have a dataset of this type:
>
+---------------------------------------------------------------------------------------------------+
> idnum       wt20       wt30       wt40       wt50       wt60   wt70  
> weight   age_ref   weightlst 
>
---------------------------------------------------------------------------------------------------
> 708   61.23497   61.23497   63.50293   61.23497   86.18255      .      
90
> 
>       60         60 
> 713   56.69905   79.37866   81.64663   104.3262          .      .     
100
> 
>       58         50 
> 721   102.0583   147.4175          .          .          .      .  
180.54
> 
>       39         30 
>
+---------------------------------------------------------------------------------------------------+
> 
> where:
> wt*: weight captured at different ages (10-yr interval)
> weight: weight at reference time
> age_ref: age at reference time
> weightlst: age at last measurement before reference
> 
> I am trying to create a measure of weight fluctuation as follows:
> 
> -----------------------------
> gen delta1 = abs(wt20 - wt30)
> gen delta2 = abs(wt30 - wt40)
> gen delta3 = abs(wt40 - wt50)
> gen delta4 = abs(wt50 - wt60)
> gen delta5 = abs(wt60 - wt70)
> egen weight_decades = rowtotal(delta1 delta2 delta3 delta4 delta5)
> -----------------------------
> 
> I would like to also capture the last interval for some people.  For
> example for id==721, I have weight measured at reference (age 39) but the
> last recorded weight is at age 30 (wt30).  Thus, the above code will only
> compute 1 interval. 
> 
> In general, if age_ref > weightlst, I need one more interval computed . 
> The preferred way would be to automate my code above to include these
> instances. Thanks for any help. 
> 
> Thomas Speidel
> 
> 
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