02-20-2012 05:46 PM
I have a list of chart numbers for a chart review. I used the retain seed methodology to produce a randomized list which nicely split the data out equally among discharge months and patient services to replicate the approximate percentages of the entire database.
However, what if I want to manipulate the volumes per patient service i.e. so that I get less newborn/obstetric cases and a higher volume of medicine charts?
Thanks very much.
04-15-2012 10:29 AM
Since posting this I've upgraded to SAS 9.3. The following code is working in that it provides a 2% sampling per PatServ but what if I want to have different values per PatServ value? For instance, what I usually do is use a Survey Sample Calculator online to come up with how many charts need to be reviewed for a 95% confidence level and 5% confidence interval. So I know how many charts I want the total to be but I want to be able to indicate how many per PatServ (either by % or number).
For example, if the sample for a database is 348 charts, I want to be able to indicate 285 (81.9%) of charts are if PatServ 10; 11 (3.2%) if PatServ = 20; 20 (5.7%) if PatServ = 30; etc.
procsurveyselect data = &import_result
method=sys rate=.02 seed=1234
Thanks for any assistance.
04-15-2012 10:53 AM
You need to create a dataset, say mySampSizes, containing PatServ and _NSIZE_ : the number of units to select from each strata, and use SAMPSIZE=mySampSizes instead of rate=. Or alternatively, you can include a variable _RATE_ and use SAMPRATE=mySampSizes.
04-15-2012 11:23 AM
Thanks for the quick response.
What I actually did, but I don't know if it is correct, was to include the sample size per PatServ (as it would be in ascending order):
procsurveyselect data= &import_result
sampsize=(285, 11,20, 0,14, 3,0, 11,4, 0,0);
This appears to have worked correctly in giving me the number of charts per patient service that I requested. Conversely, I assume I could indicate samprate() and provide the rates per PatServ.
04-15-2012 12:29 PM
That works fine, but it's fragile. There is no easy way to tell if the proper sample size is assigned to the right strata. That's why I suggested to use a dataset. In creating such a dataset, you have the opportunity to state the formal rule that decides your sample sizes. It could be something like :
create table mySampSizes as
case when count(*) < 20 then 0
end as _NSIZE_
group by PatServ
order by PatServ;
This way documents your choices and automatically assigns the sample sizes to the proper strata.