Re: st: Linking a patient file with an event file

[Carl Severson <carlseverson@gmail.com>]

I think I misread your original post.

     by id2013: gen edcount = _n

The above code will create a variable called edcount that has counts
each observation of each patient. Then try:

     reshape wide visitVariable, i(id2013) j(edcount)

Or something along those lines.

Hope that helps.
Carl

On Thu, Feb 28, 2013 at 11:13 AM, Health Services PhD
<hlthsrvcsphd@gmail.com> wrote:
> Hi Carl and others,
>
> Thanks for the quick reply. I appreciate your time.
>
> It sounds like you're suggesting that I'll end up with one observation
> per person plus a count variable, is that correct? Unfortunately, each
> visit could have different diagnosis codes and other visit-associated
> information (dates, providers) that I need to retain. Are there other
> approaches to doing so?
>
> Lisa
>
>
> On Thu, Feb 28, 2013 at 12:51 PM, Carl Severson <carlseverson@gmail.com> wrote:
>> Hi Lisa,
>>
>> You are on the right track. Try this:
>>
>>      by id2013: gen edcount = _n
>>      by id2013: gen temp = _N
>>      keep if edcount == temp
>>      drop temp
>>
>> Now you have one observation per person (making it easy to merge the
>> visit data to your sociodemographic data) and the variable edcount
>> will contain a value corresponding to the number of visits each person
>> had, which I think is what you said you needed.
>>
>> Good luck.
>> Carl
>>
>> p.s. I work with the same kind of data all the time so if you have
>> more questions, feel free to ask.
>>
>> On Thu, Feb 28, 2013 at 10:15 AM, Health Services PhD
>> <hlthsrvcsphd@gmail.com> wrote:
>>> I want to link/merge several files, but my data are complicated and
>>> I’m unsure how to proceed. I'm using Stata 11.2 for Windows.
>>>
>>> My patient file contains sociodemographic information for ~60,000
>>> patients. My event file contains information about ~20,000 visits to
>>> emergency rooms. There is a patient ID variable in each file. Many
>>> patients in my patient file will not be in my event file (because they
>>> didn't visit the emergency room). My event file has a patient ID,
>>> service date, and various other variables related to the visit.
>>>
>>> I need to merge the files so I can analyze incidence and run
>>> regression models. I've read lots about merging files, but haven't
>>> seen anything that addresses my issue yet.
>>>
>>> I assume I will need to reshape my event file from long to wide so
>>> that there is one row per patient, but everything I read about
>>> reshaping assumes that the multiple observations per patient are
>>> identified somehow. So one thing I *think* I need to do is generate a
>>> new variable that counts ED visits for each patient. I thought I might
>>> be able to do something like this: (from
>>> http://www.stata.com/support/faqs/data-management/creating-group-identifiers/)
>>>
>>> by id2013: gen edcount = 1 if _n==1
>>> replace edcount = sum(edcount)
>>>
>>> But that gives me a sequential number that doesn't restart at 1 for
>>> each new patient ID.
>>>
>>> Is reshaping the right approach, and if so, how do I best create the
>>> variable I need?
>>>
>>> Thanks in advance for your time,
>>> Lisa
>>>
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