[R-meta] Two questions about the subgroup analysis

[전경남]

Dear Wolfgang,
 
Thank you so much for your help!
Using the command you provided, I can get the p-values as I need.
I have one more question.
If only between-group variance is different under boht models,
will I get the different total variance under different models?
 
Kyungnam 
 
 
 
 
-----Original Message-----
From: "Viechtbauer Wolfgang (SP)"<wolfgang.viechtbauer at maastrichtuniversity.nl> 
To: "전경남"<fstyle71 at naver.com>; "r-sig-meta-analysis at r-project.org"<r-sig-meta-analysis at r-project.org>; 
Cc: 
Sent: 2018-02-04 (일) 21:12:06
Subject: RE: [R-meta] Two questions about the subgroup analysis
 
Dear Kyungnam,

1) The CI for each subgroup tells you whether the effect for that subgroup is significantly different from 0. If 0 is not part of the 95% CI, then you know that the effect is significantly different from 0 at alpha = .05 (two-sided). If you want the p-values for the tests, then you can find them with:

res$pval.fixed.w
res$pval.random.w

for the fixed- and random-effects models, respectively, and where 'res' is the fitted model object.

2) The "Within groups" test is the same for the fixed- and random-effects model. Hence, it is only shown once.

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-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-
>project.org] On Behalf Of ???
>Sent: Saturday, 03 February, 2018 3:45
>To: r-sig-meta-analysis at r-project.org
>Subject: [R-meta] Two questions about the subgroup analysis
>
>Dear all,
>
>I performed a subgropu analysis using the meta package.
>The following are the results of the analysis.
>I have two questions about the results.
>
>1. Is there any option that I can see the results of significant
>testsings
>about whether each effect size estimates for the two groups are zero or
>not ?
>
>2. Why could I get the results only for between groups under the random
>model?
>As you see, under the fixed effect model,
>information about both between groups and within groups are provided.
>
>Thank you for your help in advance!
>
>Kyungnam Jeon
>
>----- The results of analysis ------
>
>Number of studies combined: k = 15
>
>                        SMD            95%-CI    z  p-value
>Fixed effect model   0.0993 [ 0.0317; 0.1670] 2.88   0.0040
>Random effects model 0.1026 [-0.0407; 0.2458] 1.40   0.1605
>Quantifying heterogeneity:  tau^2 = 0.0595; H = 2.07 [1.62; 2.66]; I^2 =
>76.7% [61.8%; 85.8%]
>
>Test of heterogeneity:
>     Q d.f.  p-value
> 60.18   14 < 0.0001
>
>Results for subgroups (fixed effect model):
>                 k     SMD            95%-CI     Q    tau^2   I^2
>level = ele     10  0.1959 [ 0.1097; 0.2822] 40.71   0.0696 77.9%
>level = second   5 -0.0544 [-0.1633; 0.0544]  6.99   0.0117 42.8%
>
>Test for subgroup differences (fixed effect model):
>                   Q d.f.  p-value
>Between groups 12.48    1   0.0004
>Within groups  47.69   13 < 0.0001
>
>Results for subgroups (random effects model):
>                 k     SMD            95%-CI     Q    tau^2   I^2
>level = ele     10  0.1873 [-0.0018; 0.3764] 40.71   0.0696 77.9%
>level = second   5 -0.0538 [-0.1990; 0.0915]  6.99   0.0117 42.8%
>
>Test for subgroup differences (random effects model):
>
>                    Q d.f.  p-value
>Between groups   3.93    1   0.0475
>
>Details on meta-analytical method:
>- Inverse variance method
>- DerSimonian-Laird estimator for tau^2
>- Hedges' g (bias corrected standardised mean difference)

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