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[R-meta] Stepwise meta-regression

3 messages · Michael Dewey, Hiam S. Chemaitelly

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Dear Michael,

I am sorry for the delayed reply.

Many thanks for sharing this very useful resource. It is very informative and insightful.

I am looking at how different a priori defined factors affect the prevalence of a sexually transmitted infection in a population. The data are based on a systematic review of studies reporting the prevalence of this infection in the population of interest.

I am sorry to trouble you, but can you please clarify what you meant by " You do presumably realise that it leads to models which do not replicate on new datasets and the confidence intervals it gives do not have their usual meaning?"

Many thanks for all of your time and support to this end.

Best regards,
Hiam

Hiam Chemaitelly
Senior Research Specialist, Epidemiologist
Infectious Disease Epidemiology Group
Weill Cornell Medicine-Qatar
Education City, POBox: 24144, Doha, Qatar
Phone: + (974) 4492 8443, Fax: + (974) 4492 8422
Email: hsc2001 at qatar-med.cornell.edu

-----Original Message-----
From: Michael Dewey <lists at dewey.myzen.co.uk>
Sent: Friday, May 31, 2019 6:01 PM
To: Hiam S. Chemaitelly <hsc2001 at qatar-med.cornell.edu>; r-sig-meta-analysis at r-project.org
Cc: Laith Jamal Abu Raddad <lja2002 at qatar-med.cornell.edu>
Subject: Re: [R-meta] Stepwise meta-regression

Does
http://www.metafor-project.org/doku.php/tips:model_selection_with_glmulti_and_mumin
help?

It might help if you had stated what your scientific question is which demands variable subset selection. You do presumably realise that it leads to models which do not replicate on new datasets and the confidence intervals it gives do not have their usual meaning?

Michael
On 29/05/2019 19:30, Hiam S. Chemaitelly wrote:
--
Michael
http://www.dewey.myzen.co.uk/home.html
Disclaimer: This email and its attachments may be confidential and are intended solely for the use of the individual to whom it is addressed. If you are not the intended recipient, any reading, printing, storage, disclosure, copying or any other action taken in respect of this e-mail is prohibited and may be unlawful. If you are not the intended recipient, please notify the sender immediately by using the reply function and then permanently delete what you have received.
#
Dear Hiam

Try
https://www.stata.com/support/faqs/statistics/stepwise-regression-problems/

I know it comes from a Stata FAQ but it is a convenient summary of some 
of the sources.

For a more recent non-technical summary

@article{babyak04,
    author = {Babyak, M A},
    title = {What you see may not be what you get: a brief, nontechnical
       introduction to overfitting in regression--type models},
    journal = {Psychosomatic Medicine},
    year = {2004},
    volume = {66},
    pages = {411--421}
}

Michael
On 01/06/2019 20:00, Hiam S. Chemaitelly wrote:

  
    
  
#
Dear Michael,

Many thanks for sharing this link and article. We found these very useful to decide about next steps.

We truly appreciate your time and support.

Best regards,
Hiam

-----Original Message-----
From: Michael Dewey <lists at dewey.myzen.co.uk>
Sent: Sunday, June 2, 2019 1:54 PM
To: Hiam S. Chemaitelly <hsc2001 at qatar-med.cornell.edu>; r-sig-meta-analysis at r-project.org
Cc: Laith Jamal Abu Raddad <lja2002 at qatar-med.cornell.edu>
Subject: Re: [R-meta] Stepwise meta-regression

Dear Hiam

Try
https://www.stata.com/support/faqs/statistics/stepwise-regression-problems/

I know it comes from a Stata FAQ but it is a convenient summary of some of the sources.

For a more recent non-technical summary

@article{babyak04,
    author = {Babyak, M A},
    title = {What you see may not be what you get: a brief, nontechnical
       introduction to overfitting in regression--type models},
    journal = {Psychosomatic Medicine},
    year = {2004},
    volume = {66},
    pages = {411--421}
}

Michael
On 01/06/2019 20:00, Hiam S. Chemaitelly wrote:
--
Michael
http://www.dewey.myzen.co.uk/home.html
Disclaimer: This email and its attachments may be confidential and are intended solely for the use of the individual to whom it is addressed. If you are not the intended recipient, any reading, printing, storage, disclosure, copying or any other action taken in respect of this e-mail is prohibited and may be unlawful. If you are not the intended recipient, please notify the sender immediately by using the reply function and then permanently delete what you have received.