[R-meta] Differences between metafor / robumeta / lme4
Bernard Fernou
bern@rd@|ernou @end|ng |rom gm@||@com
Sun Jul 12 13:05:12 CEST 2020
Dear James,
Thank you very much for your prompt reply! We would like to determine
whether there is a crude association between BMI and depression symptoms in
patients with a neurodevelopmental disorder. We would like to draw a random
effects inference.
We understand the interest in trying to capture the correlation between the
effect size estimates. I have read the chapter of Gleser & Olkin (2009)
but, since it did not describe formulas when correlations are used as ES,
we did not know how to move forward with our situation. This is why we have
adopted a RVE approach.
I am very interested in trying to apply the two approaches you suggest. I
have tried to read a bit on bootstrapping in the context of meta-analysis
but that exceeded my (very basic) level of statistical knowledge.
I found some resources on metafor's website on bootstrapping (
http://www.metafor-project.org/doku.php/analyses:viechtbauer2007a).
Although I managed to implement it on our data, I was not sure that this
approach is the one you recommended to us (essentially, I did not
understand how it provides information on the correlation between our ES).
Should the data.gen function be modified to integrate the correlation
between the effect sizes?
data.gen <- function(dat, mle) {
data.frame(yi=rnorm(nrow(dat), mle$mu,
sqrt(mle$tau2 + dat$vi)), vi=dat$vi)
}
If you have some resources that could guide us, it would be very
appreciated.
Thank you so much for your invaluable help!
Bernard
Le sam. 11 juil. 2020 à 15:23, James Pustejovsky <jepusto using gmail.com> a
écrit :
> Bernard,
> Could you clarify what is the goal of your analysis? What question(s) are
> you trying to answer? And in particular, are you aiming to draw a random
> effects inference (to a broader population of studies) or a fixed effects
> inference (limited to the set of studies in the analysis)?
>
> Generally, I would recommend using an approach that captures the
> correlations between the effect size estimates (i.e., the correlation
> between the estimated correlation coefficients). As far as I can tell, none
> of the approaches you listed really does that. The robumeta and metafor
> models make arbitrary assumptions about the correlation, then use RVE to
> protect against this. But given that you have the raw data, you should be
> able to obtain all the information you would need to understand the
> correlations—either through the old Steiger 1980 formulas or (probably
> better?) by bootstrapping the set of ES estimates from each study.
>
> James
>
> > On Jul 11, 2020, at 6:15 AM, Bernard Fernou <bernard.fernou using gmail.com>
> wrote:
> >
> > Hi everyone,
> > I hope this email finds you well.
> >
> > I am trying to model the relationship between depression and BMI over
> > several studies conducted in our research lab. We have access to all
> > individual patient data.
> >
> > We have 7 seven studies in which BMI is always assessed using a
> > digital scale and a meter but in which we used various measures to assess
> > depression (self reported questionnaire / interviews / medical file).
> Each
> > study included either 1, 2 or the 3 measures of depression. The effect
> > size used is correlation.
> >
> > We have analyzed our data using 3 methods (2 two-stage approaches: robu
> > from robumeta / 3 level meta analysis with robust SE using metafor; and 1
> > one-stage approach: a mixed model using lme4).
> >
> > A complete reproducible example is provided below.
> >
> > Results from metafor and lme4 agreed (p values were not significant and
> > very similar: p = .13, .14). However, results from robumeta are quite
> > different (the p value is barely significant p = .03). I tried to use
> > several rho values in robumeta but it did not change anything. Note that
> > heterogeneity/inconsistency (assessed using tau² / I²) are very low.
> >
> > Unfortunately, as this meta analysis did not followed any systematic
> > review, we made the mistake to not pre register it and to directly
> analyze
> > the data. Therefore, we have not any proof of what analysis what thought
> as
> > primary. Even if the effet sizes are similar across 3 methods, it is
> > probable that readers will be sensitive to p-values. The choice of the
> > statistical analysis is thus critical.
> >
> > I know that one-stage and two stages approaches could differ because of
> the
> > model specification (Burke et al., 2017). Thus; I suspect that we missed
> a
> > specification differing between robumeta on the one side and both
> > metafor+lme4 on the other.
> >
> > I do not know if this mailing list is the right place to ask for help but
> > if someone could give me a feedback on the code used and on the best
> > approach to analyze our data, it would be greatly appreciated!
> >
> > Best,
> >
> > Bernard
> >
> >
> > set.seed(1234)
> > BMI<-rnorm(1000, 23, 4)
> > Depression<-rnorm(1000, 10, 2)+0.1*BMI
> > cor.test(~BMI+Depression)
> > Study<-rep(1:6, times=c(100,100,100,300,200,200))
> > Outcome<-c(rep(c("Questionnaire", "Interview"), times=c(100,200)),#first
> 3
> > studies
> > rep(c("Questionnaire", "Interview", "MedicalFile"),
> > each=100),#4th study
> > rep(c("Questionnaire", "Interview"), each=100, times=2))#5&6th
> > studies
> >
> > df<-data.frame(cbind(BMI,Depression,Study,Outcome))
> >
> > #see the structure of the data
> > df %>%
> > group_by(Study ,Outcome) %>%
> > summarise(N=n())
> >
> > corFUNC=function(x){
> > list(
> > cor.test(~as.numeric(x$BMI)+as.numeric(x$Depression))$estimate,
> > (cor.test(~as.numeric(x$BMI)+as.numeric(x$Depression))$parameter+2))
> > }
> >
> > df.cor<-split(df, list(df$Study, df$Outcome), drop=TRUE)
> > lapply(df.cor,corFUNC)
> >
> > df.meta.1<-as.data.frame(do.call(rbind, lapply(df.cor,corFUNC)))
> >
> > df.meta<-df.meta.1 %>%
> > dplyr::mutate(Study.Outcome=row.names(df.meta.1)) %>%
> > tidyr::separate(Study.Outcome, into=c("Study", "Outcome")) %>%
> > dplyr::rename("Cor"=V1,"N"=V2) %>%
> > dplyr::arrange(Study) %>%
> > dplyr::mutate(
> > yi=yi<-escalc(measure="ZCOR", ri=as.numeric(Cor), ni=as.numeric(N),
> > data=df.meta)$yi,
> > vi=yi<-escalc(measure="ZCOR", ri=as.numeric(Cor), ni=as.numeric(N),
> > data=df.meta)$vi)
> >
> > Approach1=robumeta::robu(
> > formula = yi ~ 1,
> > v=vi,
> > studynum = Study,
> > small = TRUE,
> > rho=0.3,
> > data = df.meta)
> >
> > df$BMI<-as.numeric(df$BMI); df$Depression<-as.numeric(df$Depression)
> >
> >
> Approach2=lme4::lmer(BMI~Depression+(1+Depression|Study)+(1+Depression|Outcome:Study),
> > data=df)
> >
> > Approach3=rma.mv(yi, vi, random = ~ 1 |Study/Outcome, data=df.meta)
> > robust(Approach3, cluster = df.meta$Study)
> >
> > [[alternative HTML version deleted]]
> >
> > _______________________________________________
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