topic Re: Most accurate way to count months between two date variables? in New SAS User

Most accurate way to count months between two date variables?

accintron — Wed, 15 Jan 2020 21:20:14 GMT

I've used the following code to calculate months between two date variables, however, I feel like it's not as accurate as I'd like it to be...

data readms_dist2;
set readms_dist2;

Months_btwn_adms=intck('month', PRV_DC_DT, ADM_DT);
Weeks_btwn_adms=intck('week', PRV_DC_DT, ADM_DT);
Days_btwn_adms=intck('day', PRV_DC_DT, ADM_DT);

run;

From my understanidng, the intck month function just counts if the date has "crossed" into the next month -

So if had a PRV_DC_DT was january 1 2020 and the ADM_DT was january 30 2020, then the function would return 0.

but if PRV_DC_DT was january 30 2020 and ADM_DT was february 1 2020 then the function would return 1. This is correct right? Well, that's not very accurate in calculating how many months between two dates, so what's my best option?

Thanks!

Re: Most accurate way to count months between two date variables?

novinosrin — Wed, 15 Jan 2020 21:22:52 GMT

Use 'C' for continuous

Months_btwn_adms=intck('month', PRV_DC_DT, ADM_DT,'c');

Re: Most accurate way to count months between two date variables?

Reeza — Wed, 15 Jan 2020 21:22:52 GMT

Look at the fourth parameter in the INTCK() function.

However, a month does not a standard definition, ie it could be 28 days or 31 days which can be a 10% difference there. It depends on what you need. You can use # of days or some other measure but it depends on what you're calculating and what the rules are.

Re: Most accurate way to count months between two date variables?

accintron — Wed, 15 Jan 2020 21:36:24 GMT

Thank you!

Re: Most accurate way to count months between two date variables?

accintron — Wed, 15 Jan 2020 21:38:21 GMT

Yes, ok, I see that's what the other post did with the 'c' for continuous. This is good enough for my purposes 🙂

Re: Most accurate way to count months between two date variables?

Reeza — Wed, 15 Jan 2020 21:44:03 GMT

This is the reason the standards were set at 30/90/180 re-admission rates though 🙂

Re: Most accurate way to count months between two date variables?

accintron — Thu, 16 Jan 2020 14:31:14 GMT

Makes sense. Is there a way to count by 30 day intervals? Can you use that as the fourth parameter?

Re: Most accurate way to count months between two date variables?

novinosrin — Thu, 16 Jan 2020 14:38:39 GMT

Hi @accintron Not quite using the fourth argument. But you can use an Interval Multiplier to Create a Custom Interval.

For example day30 as the interval in your case

Months_btwn_adms=intck('day30', PRV_DC_DT, ADM_DT);

Re: Most accurate way to count months between two date variables?

accintron — Thu, 16 Jan 2020 14:39:58 GMT

Ah ok! This is great. thanks so much. I'll check out both!

Re: Most accurate way to count months between two date variables?

novinosrin — Thu, 16 Jan 2020 14:43:53 GMT

IMHO, you would still need to test carefully with "C" and without "C"

Months_btwn_adms=intck('day30', PRV_DC_DT, ADM_DT,"c");

It seems quite likely you would need a 'C' for your custom interval too

Re: Most accurate way to count months between two date variables?

accintron — Thu, 16 Jan 2020 14:54:01 GMT

Ok, thank you for this advice. I will try out all three! 🙂