[R-meta] Adding a 0.5 continuity correction

[Guido Schwarzer]

Am 05.07.22 um 16:56 schrieb Tharaka S. Priyadarshana:

> Hello, everyone,
>
> Is it a common practice to add a 0.5 continuity correction for zero cells
> when measuring MD or SMD as the outcome measure?

Hi Tharaka,

For ratio measures like OR, RR or ROM one does not want to have a zero 
in the nominator or denominator. Accordingly, a continuity correction is 
typically used.  Measures based on differences like MD or SMD do not 
have this problem.

library(meta)
m.noincr <- metabin(rep(0, 2), 100:101, 1:2, 100:101, sm = "RR",
   incr = 0, overall = FALSE, overall.hetstat = FALSE)
summary(m.noincr)
m.withincr <- update(m.noincr, incr = 0.5)
print(summary(m.withincr), ma = FALSE)

Best,

Guido

Dr. Guido Schwarzer
Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Postal address: Zinkmattenstr. 6a, D-79108 Freiburg

Mail: sc using imbi.uni-freiburg.de
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