[EpiData-list] Question re defining a new variable in EpiData Analysis

epidata-list at lists.umanitoba.ca epidata-list at lists.umanitoba.ca
Thu May 31 02:07:07 CDT 2012

On 2012-05-31 04:00, epidata-list at lists.umanitoba.ca wrote:
> Hello,
> I am a relatively new EpiData user and am now using EpiData Analysis.
> In EpiData Analysis I would like to create a new variable which will be the number of days between two dates which I have collected in my EpiData dataset.  I have started with "define" and the name of the new variable and the new variable will be a numeric variable of length 4. i.e:
> define smeartoreg1 ####
> However, I am having difficulty with the code for defining the number of days between two existing dates and would appreciate some advice on this. I think I am making a simple mistake that can easily be fixed.
The simple sollution is to make an expression where the two date 
variable are subtracted from eachother:

smeartoreg1 = datevarend - datevarstart

This will give you the number of days between two dates in the variables.

Here is a small example of how it works - paste this into the Editor of 
Analysis (F5) and run (F9) then you should
see how the date differences are calculated:


generate 20
gen d d1 = dmy(1,1,2000) + _n
gen d d2 = dmy(1,2,2000) + (_n * 2)
gen i daysdiff = d2 - d1


Kind regards,
Torsten Bonde Christiansen
EpiData Association.

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