Bookmark and Share

Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, statalist.org is already up and running.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: RE: comparing two linear slopes


From   "Kieran McCaul" <Kieran.McCaul@uwa.edu.au>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: comparing two linear slopes
Date   Sat, 30 Oct 2010 07:56:42 +0800

...


just out of curiosity, how did you establish that the relationship was
linear for the intervening years?



-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Ashwin
Ananthakrishnan
Sent: Saturday, 30 October 2010 4:40 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: comparing two linear slopes

Hi, 

I'm examining the rate of change of two proportions over time. I'd be
grateful if someone could help me figure this out: 

I'm looking at the proportional increase in two specific disease (as a
proportion of all hospitalizations) over time and need to see if the
rate of increase for one disease is statistically greater than the rate
of increase for disease 2. 

I have the sum totals for the numerators (i.e disease 1 or disease 2)
and denominators (total hospitalization 1 and total hospitalizations 2)
for the start and the end year (the relationship is linear for the
intervening years - that's been looked at). 

Is there a way to compare these two trends statistically to say that the
4-fold increase for disease 1 is significant greater than the 2-fold
increase for disease 2? 

Should i calculate the annual percent change for each disease and then
use the two-sample t test? How i get the Std dev for the annual percent
change? 

Thanks, 

Ashwin


      
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index