Skip Navigation

This Article
Right arrow Full Text (PDF)
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (6)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by JOHANNESSEN, T.
Right arrow Articles by PETERSEN, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by JOHANNESSEN, T.
Right arrow Articles by PETERSEN, H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Family Practice Vol. 7, No. 4, 325-328
© Oxford University Press 1990

research-article

Statistical Aspects of Controlled Single Subject Trials

TERJE JOHANNESSEN, DANIEL FOSSTVEDT and HERMOD PETERSEN*

Department of Community Medicine and General Practice, University of Trondheim
*Section of Gastroenterology, Deparment of Medicine, Trondheim Regional and University Hospital Norway

Correspondence to: Terje Johannessen, Department of Community Medicine and General Practice, University of Trondheim, Eirik Jarls gt. 10, N-7030 Trondheim, Norway

Randomized controlled trials in groups and single subjects differ in several statistical aspects. In group trials the experimental unit is a randomly selected subject from a predefined population and this subject is randomly assigned to a treatment.Outcome is confined to average effects which can be generalized to the specific population, but which do not necessarily apply to individual persons. In single subject trials the experimental unit is a treatment period and each treatment period is randomly allocated in a multiple cross-over sequence of periods. The single subject is only representative of itself, but similar responses in corresponding single subject trials may justify careful extrapolation of the results.

Single subject trials have a high risk of Type II errors. However, the randomization procedure chosen and the type of statistical test applied may enhance the statistical power of such trials. Internal validity depends on modelling the trial design to the clinical features, drug properties and statistical requirements, while reliability is determined by the reproducibility of the trial response.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.