Error message in meta-analysis package Metafor-weights =""

forest(result.md)

Dear Amoatwi,

This way of using the escalc() function has been deprecated. It might be
added back once there is actually any benefit from having this
functionality, but for years it just meant that I had to maintain two
different ways of doing the exact same thing without any additional
benefits.

Best,
Wolfgang

--
Wolfgang Viechtbauer, Ph.D., Statistician | Department of Psychiatry and

Neuropsychology | Maastricht University | P.O. Box 616 (VIJV1) | 6200 MD

Maastricht, The Netherlands | +31 (43) 388-4170 | http://www.wvbauer.com

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of K Amoatwi
Sent: Tuesday, 16 June, 2020 4:50
To: r-help at r-project.org
Subject: [R] Error message in meta-analysis package Metafor-weights =""

Dear All,
I am using the example from one of the tutorial about "Metafor" package

and

"escalc" function, to learn how this package can be applied to do
meta-analysi; the code and the data is directly from the tutorials but
"weights=freq" option in the escalc function is given me error message
This is the code below:

library(metafor) # Load package
#####DATASET 1: BCG Vaccine Trials
data(dat.bcg) # BCG meta-analytic dataset

##Formula based Specification
##That is, what if I have multiple rows per study, corresponding to
difference treatment groups?

library(reshape2) # Load package for data reshaping

bcg.long <- melt(dat.bcg[, c("trial", "tpos", "tneg", "cpos", "cneg")], id
= "trial")
bcg.long$pos <- ifelse(bcg.long$var == "tpos" | bcg.long$var == "cpos", 1,
0)
bcg.long$group <- ifelse(bcg.long$var == "tpos" | bcg.long$var == "tneg",
1, 0)

##sample of the data, the first 6 rows
head(bcg.long)
 trial variable value pos group
1     1     tpos     4     1     1
2     2     tpos     6     1     1
3     3     tpos     3     1     1
4     4     tpos    62    1     1
5     5     tpos    33    1     1
6     6     tpos   180   1     1

##Now applying the " escalc " function

escalc(factor(pos)~factor(group)| factor(trial),weights = value,data =
bcg.long, measure = "OR")

##Then I got this error message
Error in escalc(factor(pos) ~ factor(group) | factor(trial), weights =
value,  :
 object 'value' not found

I used the same data with different example from another author and got a
similar error message
Second code with the same data but different coding
Sample data

with the first 6 rows of the rearranged data shown below. (T=treatment,
C=Control group, Out=outcome whether positive or negative, and then
frequency)
   study grp out freq
1        1    T    +      4
2        1    T    -    119
3        1    C   +      11
4        1    C   -     128
5        2    T   +        6
6        2    T   -      300

escalc(out ~ grp | study, weights = freq, data = dat.fm, measure = "OR")

Error in escalc(out ~ grp | study, weights = freq, data = dat.fm,

measure =

"OR") :
 object 'freq' not found

I am not sure what I am doing wrong since both authors were able to get
their results while I am getting error messages.

Any help will be very much appreciated

Amoatwi