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From |
"Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: new program sampsi_sccs |

Date |
Mon, 20 Apr 2009 09:04:46 -0700 |

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: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Philip Ryan Sent: Sunday, April 19, 2009 4:31 PM To: statalist@hsphsun2.harvard.edu 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/

**Follow-Ups**:**st: RE: RE: new program sampsi_sccs***From:*"Philip Ryan" <philip.ryan@adelaide.edu.au>

**References**:**st: new program sampsi_sccs***From:*"Philip Ryan" <philip.ryan@adelaide.edu.au>

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