[R-meta] Inconsistency Testing

Dr. Gerta Rücker ruecker @end|ng |rom |mb|@un|-|re|burg@de
Tue Mar 9 23:47:03 CET 2021

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?



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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