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Re: st: T-test and F-test


From   Roger Newson <r.newson@imperial.ac.uk>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: T-test and F-test
Date   Mon, 5 Jul 2010 12:42:16 +0100

Yes. The data may be compatible with the possibility that the first difference is zero, and compatible with the possibility that the second difference is zero, but not compatible with the possibility that BOTH differences are zero. So, at least one of the differences seems to be non-zero, but the data are insufficient to be sure which one is non-zero, or to be sure that BOTH are nonzero.

I hope this helps.

Best wishes

Roger


Roger B Newson BSc MSc DPhil
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton Campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: r.newson@imperial.ac.uk
Web page: http://www.imperial.ac.uk/nhli/r.newson/
Departmental Web page:
http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/

Opinions expressed are those of the author, not of the institution.

On 05/07/2010 12:36, natasha agarwal wrote:
Dear everyone,

Can anyone explain me why the t-test statistics for variables in the
model are statistically insignificant but when tested for joint
significance (F-test) they are jointly significant?

Thanks
Natasha
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