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st: AW: Automating intervals creation


From   "Martin Weiss" <martin.weiss1@gmx.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: AW: Automating intervals creation
Date   Tue, 25 Aug 2009 22:44:36 +0200

<>


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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