[R-meta] Outliers in meta analysis

[Mutlu Umaroglu]

Dear all,

I am interested in Meta Analysis and studying on outliers. There are 
several method proposed to examine outliers (Viechtbauer 2010).
According to metafor packages following studies are outlier in this 
example. How can we deside exactly which studies are
influences/outliers?

Sincerely,
Mutlu


library("metafor")
data <- dat.bcg
dat1 <- escalc(measure="RD", ai=tpos, bi=tneg, ci=cpos, di=cneg, 
data=data)
res1 <- rma(yi, vi, method="DL",data=dat1)
influence(res1)

    rstudent  dffits cook.d  cov.r tau2.del   QE.del    hat  weight    
dfbs inf
1   -1.4026 -0.0889 0.0079 0.9976        0 273.7960 0.0031  0.3060 
-0.0891
2   -3.6289 -0.3913 0.1526 0.9563        0 260.2482 0.0067  0.6656 
-0.4008
3   -1.7694 -0.1874 0.0351 0.9961        0 271.6713 0.0084  0.8424 
-0.1885
4   -2.5810 -1.9330 2.4532 0.7580        0 167.7548 0.1190 11.9010 
-1.9186   *
5    1.2615  0.5217 0.2813 1.1661        0 276.3026 0.1143 11.4253  
0.5218
6   -9.2559 -1.4557 2.0527 0.6846        0 179.5183 0.0113  1.1260 
-1.7385   *
7   -0.8835 -0.2354 0.0551 1.0453        0 271.0926 0.0545  5.4510 
-0.2361
8    1.6691  1.4621 3.6567 1.8187        0 263.8946 0.1296 12.9579  
1.5125   *
9    1.1381  0.5412 0.3114 1.2042        0 274.9691 0.1216 12.1644  
0.5424
10  -3.4172 -0.9551 0.8758 0.9605        0 248.2341 0.0520  5.2024 
-0.9795   *
11   1.3748  1.1033 1.7292 1.5523        0 274.9184 0.1287 12.8677  
1.1272   *
12   1.8398  0.7986 0.6771 1.2027        0 274.4115 0.1217 12.1716  
0.8004   *
13   1.6603  1.3631 2.9509 1.7076        0 270.6094 0.1292 12.9187  
1.4029   *