[R] Error message in meta-analysis package Metafor-weights =""

[K Amoatwi]

Hi Wolfgang and All,
I am still practising my meta-analysis with the "Metafor" package, I tried
to run the code for "Forest plot" and got error message as shown below:
forest(result.md)
> forest(result.md)
Error in UseMethod("forest") :
  no applicable method for 'forest' applied to an object of class
"c('rma.uni', 'rma')"

Thank you in advance for your support

regards
Kobby


On Tue, Jun 16, 2020 at 12:50 PM Viechtbauer, Wolfgang (SP) <
wolfgang.viechtbauer using maastrichtuniversity.nl> wrote:

> 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 using r-project.org] On Behalf Of K Amoatwi
> >Sent: Tuesday, 16 June, 2020 4:50
> >To: r-help using 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
>

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