library(meta)

m1 <- metagen(rep(1, 100), c(rep(0.1, 10), rep(0.2, 90)), sm = "MD")
##
funnel(m1)

m1.jit1 <- m1
m1.jit1$TE <- jitter(m1$TE)
m1.jit1$seTE <- jitter(m1$seTE)
##
funnel(m1.jit1)

m1.jit2 <- m1
m1.jit2$TE <- jitter(m1.jit2$TE, 0.5)
m1.jit2$seTE <- jitter(m1.jit2$seTE, 0.5)
##
funnel(m1.jit2)


m1.for <- metafor::rma(yi = rep(1, 100),
                       sei = c(rep(0.1, 10), rep(0.2, 90)),
                       measure = "MD")
metafor::funnel(m1.for)

m1.for.jit <- m1.for
m1.for.jit$yi <- jitter(m1.for.jit$yi)
m1.for.jit$vi <- jitter(sqrt(m1.for.jit$vi))^2
##
metafor::funnel(m1.for.jit)
