 |
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: RE: new program sampsi_sccs
I downloaded this program and played with it a bit. Here is one bit of
output. At the end you may note that the number of events required in
unexposed subjects if -6. I may have chosen dopey inputs, but I don't
think I can envision any group with -6 events. Phil - or someone - can
you help? I tried another combination and got -6 events needed...
. sampsi_sccs, rho(3) method(age)
Signed root likelihood method controlling for age effects
input number of age groups (e.g. 5)
. 5
input age specific incidence [relative to age group 1] in age group 2
. 3
input age specific incidence [relative to age group 1] in age group 3
. 5
input age specific incidence [relative to age group 1] in age group 4
. 7
input age specific incidence [relative to age group 1] in age group 5
. 7
input length of observation period for age group 1
. 10
input length of observation period for age group 2
. 10
input length of observation period for age group 3
. 10
input length of observation period for age group 4
. 10
input length of observation period for age group 5
. 10
input post exposure risk period [assumed the same for each group]
. 10
input proportion of subjects exposed during obs period in age group 1
. .2
input proportion of subjects exposed during obs period in age group 2
. .2
input proportion of subjects exposed during obs period in age group 3
. .3
input proportion of subjects exposed during obs period in age group 4
. .3
input proportion of subjects exposed during obs period in age group 5
. .3
==================================================================
========== sample size for SCCS Design with age effects ==========
==================================================================
2-tailed alpha is: .05
power is: .8
relative incidence associated with exposure is: 3
common post-exposure risk period is: 10
total number of events required in exposed subjects is: 32
total number of events required in unexposed subjects is: -6
Total number of events required is: 26
==================================================================
.
Tony
Peter A. Lachenbruch
Department of Public Health
Oregon State University
Corvallis, OR 97330
Phone: 541-737-3832
FAX: 541-737-4001
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Philip Ryan
Sent: Sunday, April 19, 2009 4:31 PM
To: [email protected]
Subject: st: new program sampsi_sccs
Listers
Thanks again to Kit Baum, a new program -sampsi_sccs- is now available
on
the SSC server.
-sampsi_sccs- calculates sample sizes for self-controlled case series
study
designs. Full refs to a tutorial on this type of study and to Musonda et
al's paper on sample size estimation are included in the accompanying
help
file.
Requires Stata v10
To check it out:
ssc describe sampsi_sccs
Philip Ryan
University of Adelaide
South Australia
*
* 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/