Re: st: add up the total stay

[Arun Rajamohan <arajamoh@uwo.ca>]

Hi,

I am not sure what you mean by database. Hopefully it is convertible  
to excel or raw or csv file. I draged the sample data from your email  
and saved it as a raw file. Then I loaded it into stata using infix. T

Your sample dataset is,

SD101 05-Nov-05 05-Nov-05
SD101 05-Nov-05 11-Nov-05
SD101 28-Apr-05 28-Apr-05
SD105 03-Jul-06 03-Jul-06
SD105 29-Mar-06 29-Mar-06
SD105 13-Jan-06 14-Jan-06
SD105 10-Jan-06 13-Jan-06
SD105 24-May-04 25-May-04
SD217 22-Sep-05 22-Sep-05

I  sucked it up into stata  using infix ...

infix str id 1-5 str d1 7-8 str m1 10-12 y1 14-15 str d2 17-18 str m2  
20-22 y2 24-25 using ~/desktop/stay.raw, clear

Now you will have your data in stata looking like this...

id d1 m1 y1 d2 m2 y2
SD101 05 Nov 05 05 Nov 05
...

Then you may have to add 2000 to the year values.

[I would appreciate if someone can update me on an alternate method.  
Some of my own datasets have years in the format 96, 97, 01, 04 etc.  
instead of 1996, 1997, 2001, 2004... Stata date system does not like  
years in 2 digit format. Am I right? I've always had to use a do file  
to sort through the years and convert them.]


Then I recombine the date values using
 generate came=d1+m1+y1
 generate went=d2+m2+y2
to make it look like this,


     +-------------------------------+
     |    id        came        went |
     |-------------------------------|
  1. | SD101   05Nov2005   05Nov2005 |
  2. | SD101   05Nov2005   11Nov2005 |
  3. | SD101   28Apr2005   28Apr2005 |
  4. | SD105   03Jul2006   03Jul2006 |
  5. | SD105   29Mar2006   29Mar2006 |
     |-------------------------------|
  6. | SD105   13Jan2006   14Jan2006 |
  7. | SD105   10Jan2006   13Jan2006 |
  8. | SD105   24May2004   25May2004 |
     +-------------------------------+

Now if you format your variables 'came' and 'went' into date  
variables by using,
gen chkin = date(came,"DMY")
gen chkout = date(went,"DMY")
 you should get,

    +------------------------------------------------+
     |    id        came        went   chkin   chkout |
     |------------------------------------------------|
  1. | SD101   05Nov2005   05Nov2005   16745    16745 |
  2. | SD101   05Nov2005   11Nov2005   16745    16751 |
  3. | SD101   28Apr2005   28Apr2005   16554    16554 |
  4. | SD105   03Jul2006   03Jul2006   16985    16985 |
  5. | SD105   29Mar2006   29Mar2006   16889    16889 |
     |------------------------------------------------|
  6. | SD105   13Jan2006   14Jan2006   16814    16815 |
  7. | SD105   10Jan2006   13Jan2006   16811    16814 |
  8. | SD105   24May2004   25May2004   16215    16216 |
     +------------------------------------------------+

Now chkin and chkout are actually number of days from 1 Jan 1960.  
Read more about this at,
http://www.ats.ucla.edu/stat/stata/modules/dates.htm

Now using generate, you should be able to subtract chkin and chkout  
and obtain the stay duration.

To convert a 0 duration to 0.5,

replace dur=0.5 if dur==0

Hope it helps

-A

On 11-Oct-07, at 3:33 PM, STATA Dndee wrote:


> Dear all
> I have a database form visitors stayed in one or more
> departments during each visit.  I want to calculate
> total length of stay during each visit. I need to
> calculate something like those I calculated manually
> under columns “Date came-Date went” and “total stay
> each visit”. If Date came= Date went, then the stay
> would be 0.5 and not zero.
> Your help is really appreciated.
> All the bests
>
> ID DateCame DateWent DateCame-DateWent
> TotalStayEachVisit
> SD101 05-Nov-05 05-Nov-05 0.5 _
> SD101 05-Nov-05 11-Nov-05 6 6.5
> SD101 28-Apr-05 28-Apr-05 0.5 0.5
> SD105 03-Jul-06 03-Jul-06 0.5 0.5
> SD105 29-Mar-06 29-Mar-06 0.5 0.1
> SD105 13-Jan-06 14-Jan-06 1 _
> SD105 10-Jan-06 13-Jan-06 3 4
> SD105 24-May-04 25-May-04 1 1
> SD217 22-Sep-05 22-Sep-05 0.5 0.5
>
>
>
>
>       ___________________________________________________________
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> *
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Arun Rajamohan
Department of Biology
Room 360, Biological & Geological Sciences Building
1151 Richmond Street North
The University of Western Ontario
London, ON N6A 5B7 CANADA

Office: + 1-519-661-2111 ext 80582
Office Fax: + 1-519-661-3935


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