Is a waiting list control group a quasi-experimental design?
Steve Simon, P.Mean Consulting
waiting list control group as a quasi-experimental design. I say no,
there's nothing "quasi" about it. It's as good as any other randomized
design, with the one caveat that it can't detect changes in the long
term, only the short term. What do you all think?
Just to be sure I'm describing things properly, there are a large number
of practices that are being studied. We randomly assign half of the
practices to receive the intervention at the beginning of year 2. The
other half receives the intervention at the beginning of year 3. For
every practice, we get a full year's worth of data in years 1, 2, and 3.
Thanks in advance for your help.
--
Steve Simon, Standard Disclaimer
Sign up for The Monthly Mean, the newsletter that
dares to call itself "average" at www.pmean.com/news
ציפי שוחט
--
To post a new thread to MedStats, send email to MedS...@googlegroups.com .
MedStats' home page is http://groups.google.com/group/MedStats .
Rules: http://groups.google.com/group/MedStats/web/medstats-rules
Bland, M.
trial and certainly not quasi-experimental. You can use all three years
of data, in which case it is a stepped wedge design.
See e.g.:
The stepped wedge trial design: a systematic review
Celia A Brown and Richard J Lilford
BMC Medical Research Methodology 2006, 6:54 doi:10.1186/1471-2288-6-54
Design and analysis of stepped wedge cluster randomized trials
Michael A. Hussey, James P. Hughes
Contemporary Clinical Trials 28 (2007) 182�191
Martin
Steve Simon, P.Mean Consulting wrote:
> I'm helping with a grant and the person writing the grant describes
> the waiting list control group as a quasi-experimental design. I say
> no, there's nothing "quasi" about it. It's as good as any other
> randomized design, with the one caveat that it can't detect changes in
> the long term, only the short term. What do you all think?
>
> Just to be sure I'm describing things properly, there are a large
> number of practices that are being studied. We randomly assign half of
> the practices to receive the intervention at the beginning of year 2.
> The other half receives the intervention at the beginning of year 3.
> For every practice, we get a full year's worth of data in years 1, 2,
> and 3.
>
> Thanks in advance for your help.
--
***************************************************
J. Martin Bland
Prof. of Health Statistics
Dept. of Health Sciences
Seebohm Rowntree Building Area 2
University of York
Heslington
York YO10 5DD
Email: mb...@york.ac.uk
Phone: 01904 321334 Fax: 01904 321382
Web site: http://martinbland.co.uk/
Statement by the University of York:
This email and its attachments may be confidential and are intended solely for the use of the intended recipient. If you are not the intended recipient of this email and its attachments, you must take no action based upon them, nor must you copy or show them to anyone. Please contact the sender if you believe you have received this email in error.
Any views or opinions expressed are solely those of the author and do not necessarily represent those of The University of York.
***************************************************
Kornbrot, Diana
Assuming that there are enough practices that mean differences across randomly assigned practices are indeed random.
The problem is explaining this to your colleague. In ‘typical’ waiting list designs, people in ONE practice on waiting list are compared with treated people in same practice. That is quasi, as there may be differences between groups on other variables, such as seriousness of condition, age, sex, etc. Consequently, waiting list designs get uniformly labelled ‘quasi’.
The difficulty is explaining this clearly, not only to your colleague, but also to the grant awarder’s referees, who may also be labouring under delusion that all waiting list designs are quasi experimental
Good luck!!
Best
Diana
On 01/09/2010 10:09, "Bland, M." <mb...@york.ac.uk> wrote:
If you use just the Year 2 data, this is an ordinary cluster randomised
trial and certainly not quasi-experimental. You can use all three years
of data, in which case it is a stepped wedge design.
See e.g.:
The stepped wedge trial design: a systematic review
Celia A Brown and Richard J Lilford
BMC Medical Research Methodology 2006, 6:54 doi:10.1186/1471-2288-6-54
Design and analysis of stepped wedge cluster randomized trials
Michael A. Hussey, James P. Hughes
Contemporary Clinical Trials 28 (2007) 182–191
--
To post a new thread to MedStats, send email to MedS...@googlegroups.com .
MedStats' home page is http://groups.google.com/group/MedStats .
Rules: http://groups.google.com/group/MedStats/web/medstats-rules
Professor Diana Kornbrot
email: d.e.ko...@herts.ac.uk
web: http://web.me.com/kornbrot/KornbrotHome.html
Work
Centre for Lifespan & Chronic Illness Research, CLiCIR
School of Psychology
University of Hertfordshire
College Lane, Hatfield, Hertfordshire AL10 9AB, UK
voice: +44 (0) 170 728 4626
Home
19 Elmhurst Avenue
London N2 0LT, UK
voice: +44 (0) 208 883 3657
mobile: +44 (0) 7855 415 425
fax: +44 (0) 870 706 4997
Brett Magill
is being studied, time (or more specifically history) may or may not
be a significant factor. It's likely you can discard this as a
concern for most applications. Biological processes aren't likely to
respond to political climates or historical events. But if you're
studying a social or psychological phenomena, this could be an
important issue.
On Wed, Sep 1, 2010 at 4:09 AM, Bland, M. <mb...@york.ac.uk> wrote:
> If you use just the Year 2 data, this is an ordinary cluster randomised
> trial and certainly not quasi-experimental. You can use all three years of
> data, in which case it is a stepped wedge design.
>
> See e.g.:
>
> The stepped wedge trial design: a systematic review
> Celia A Brown and Richard J Lilford
> BMC Medical Research Methodology 2006, 6:54 doi:10.1186/1471-2288-6-54
>
> Design and analysis of stepped wedge cluster randomized trials
> Michael A. Hussey, James P. Hughes
> Contemporary Clinical Trials 28 (2007) 182–191
>
> Martin