[R-meta] Inconsistency Testing

[Sean]

Hi Dr. Rücker,

- Let A, B, C, D be some fungicides, do I understand it correctly that
treatments are combinations in the sense of A+B, A+C+D, A+B+C etc.?

*Yes, that is correct. *

- In each trial, several of these combinations are compared?

*Yes. *

- "Design" is meant to be the notion in network meta-analysis, thus "A
vs A+B vs A+B+C" would be a possible design?

*Yes I think you have it, for example, trial 1 had A+B, A+C+D, and A+B+C as
its treatments and trial 2 had A+C, A+D, and A+C+D, and so on. *

Which R package do you use?

*metafor*

Best,

Sean


On Tue, Mar 9, 2021 at 5:47 PM Dr. Gerta Rücker <
ruecker using imbi.uni-freiburg.de> wrote:

> Dear Sean,
>
> At first, I have to understand your problem. You mention treatments that
> are combinations of fungicides, and you mention designs. To clarify
> these notions, my questions are:
>
> - Let A, B, C, D be some fungicides, do I understand it correctly that
> treatments are combinations in the sense of A+B, A+C+D, A+B+C etc.?
>
> - In each trial, several of these combinations are compared?
>
> - "Design" is meant to be the notion in network meta-analysis, thus "A
> vs A+B vs A+B+C" would be a possible design?
>
> (A different possibility is that you do not have combinations of
> treatments in the sense above, but - simpler - different designs such as
> A, B, C in one trial and A, C, D in another trial.)
>
> Could you clarify these notions?
>
> Which R package do you use?
>
> Best,
>
> Gerta
>
> Am 09.03.2021 um 23:22 schrieb Sean:
> > Hello everyone,
> >
> >
> > I’ve been stuck on a question about inconsistency testing for quite
> > some time, but first a little simplified background:
> >
> >
> > I’ve calculated effect sizes for all treatments from 50 independent
> > trials conducted over the past 10 years. These treatments are
> > different fungicides applied to a plant to control a foliar pathogen.
> > Throughout those 10 years, researchers tested 20 different products,
> > and a treatment (4-15 per trial) is different combinations of usually
> > 1-6 of those fungicides. There was no coordination over those 10 years
> > in experimental design, so no treatment was truly replicated. Instead,
> > what I’ve done is reduce treatments into larger categories based on
> > the modes of action of those fungicides. This has allowed me to have
> > enough similarly coded treatments to perform a network meta-analysis.
> > That went all well and good, however, when it comes to inconsistency
> > testing, I have as many study designs as I have studies. 50
> > independent trials, 50 designs.
> >
> >
> > Can I even technically perform inconsistency testing? What I've read
> > in the literature doesn't seem to account for my situation. If not,
> > what does this mean for my meta-analysis? Do I truly need to perform
> > inconsistency testing?
> >
> >
> > Thank you all for your time, hope your week is going well!
> >
> >
> > Sean
> >
> > _______________________________________________
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>

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