# interpretation of meta-regression in meta-analysis for number of participants explanatory variable

I have a meta-analysis with continuous variables, the melhroz study which I defined in the following dataframe

library(meta)
library(metafor)
author  <- c('Hesse','Hesse','Hsieh', 'Kuther','Liao','Wu')
year    <- c(2005, 2014, 2011,2010,2011,2012)
mean.e  <- c(22.45,25.2,0.13,6.89,0.25,3.26)
sd.e    <- c(15.14,11,0.19,9.995,0.17,7.16)
total.e <- c(22,25,12,11,10,14)
mean.c  <- c(17.27,16,0.06,8.49,0.03,-2.88)
sd.c    <- c(13.95,15.7,0.32,11.33,0.28,9.56)
total.c <-c(22,25,6,10,10,28)

melhroz.data <- data.frame(author, year, mean.e, sd.e, total.e, mean.c, sd.c, total.c)
# str(melhroz.data)
# melhroz.data


I defined two groups: studies with less than 14 participants and studies with more than 14 participants in the experimental group and run a meta-regression model

melhroz.data\$nro_experimental <- c(">=14", ">=14", "<14", "<14", "<14", ">=14")

meta1 <- metacont(total.e, mean.e, sd.e,
total.c, mean.c, sd.c,
data=melhroz.data, sm="SMD", comb.fixed=gs("comb.fixed"))

mr1 <- metareg(meta1, nro_experimental)
mr1


With the following results

Test for Residual Heterogeneity:
QE(df = 4) = 3.4174, p-val = 0.4905

Test of Moderators (coefficient(s) 2):
QM(df = 1) = 0.5462, p-val = 0.4599

Model Results:

estimate      se    zval    pval    ci.lb   ci.ub
intrcpt                 0.3221  0.2711  1.1881  0.2348  -0.2092  0.8534
nro_experimental>=14    0.2398  0.3245  0.7391  0.4599  -0.3962  0.8758


So I have no statistical significant results but what does it mean the 0.2398 estimate value? It means that if I had obtained significant pvalue the effect size would have increased in 23.98% for the studies with >= 14 participants?

• I would check the manual of the software if I were in this situation. – user158565 Dec 11 '18 at 15:28