[R-meta] Specifying variable names in metafor::vec2mat()

Tue, Sep 12, 2023 8:35 AM

Thank you, Wolfgang. When you say "it depends on the ordering of the values
in coef(res)", could you please elaborate on how exactly the user should
follow that ordering when specifying the "dimnames=" esp. when the number
of variables is larger?

For example, below, I have 8 variables with their names being `c("L2R",
"L2DA", "L2DF", "L2V", "L2G", "L2P", "L2M", "L2L")`. But I wonder how to
order them correctly in "dimnames="?

In fact, I think I'm getting the order for 7 of them right `c("L2DA",
"L2DF", "L2G", "L2L", "L2M", "L2P", "L2V")` but don't know where to put
"L2R" in that mix?

dat <- read.csv("https://raw.githubusercontent.com/ilzl/i/master/j.csv")

dat1 <- escalc("COR", ri = ri, ni = N, data = dat)

dat2 <-
transform(dat1,var1.var2=apply(dat1[c("var1","var2")],1,paste0,collapse="."))

res <- rma(yi~var1.var2+0, 1, data=dat2)

vec2mat(coef(res), dimnames = ????)

Many thanks for your expertise,
Yuhang

On Tue, Sep 12, 2023 at 1:06?AM Viechtbauer, Wolfgang (NP) <

wolfgang.viechtbauer at maastrichtuniversity.nl> wrote:

Dear Yuhang,

Since coef(res) is of length 6, vec2mat() will put these values (i.e., the
estimated average correlations) into a 4x4 (correlation) matrix. Given the
ordering of the values in coef(res), the appropriate dimension names would
be something like this:

vec2mat(coef(res), dimnames=c("acog","asom","conf","perf"))

However, there is no general rule for this, as it depends on the ordering
of the values in coef(res).

I have tried to make various functions in metafor behave in a consistent
manner when it comes to ordering certain elements, but in this case, it is
really up to the user to check that adding dimension names even makes sense
for the resulting matrix. For example:

vec2mat(sample(coef(res)))

is perfectly fine in principle (albeit a bit weird), but it no longer
makes sense to say that all values in the first column/row pertain to the
correlations between one of the four variables and the other three
variables (unless you get lucky) and so on.

But say the coefficients had been ordered like this:

coef(res)[c(3,5,6,1,2,4)]

Then the appropriate dimension names would be:

vec2mat(coef(res)[c(3,5,6,1,2,4)], dimnames=c("perf","acog","asom","conf"))

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:

r-sig-meta-analysis-bounces at r-project.org] On

Behalf Of Yuhang Hu via R-sig-meta-analysis
Sent: Monday, 11 September, 2023 5:32
To: R meta
Cc: Yuhang Hu
Subject: [R-meta] Specifying variable names in metafor::vec2mat()

Hello Everyone,

I'm using the metafor::vec2mat() as shown in the toy example below.
However, I wonder how I should specify the order of the variables' names
defined in "dimnames=" when converting the vector of coefficients to a
correlation matrix using metafor::vec2mat()?

Is there generally a rule or a technique to order the variables' names
correctly in "vec2mat()", especially if there are many variable names?

Thanks,
Yuhang

# EXAMPLE:
tmp <- rcalc(ri ~ var1 + var2 | study, ni=ni, data=dat.craft2003)
V <- tmp$V
dat <- tmp$dat

res <- rma.mv(yi~ var1.var2 - 1, V,
             random = ~  var1.var2| study, struct = "UN",
             data=dat)

vec2mat(coef(res), dimnames= ??????)

[R-meta] Specifying variable names in metafor::vec2mat()

Thread (4 messages)