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tips:models_with_or_without_intercept

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tips:models_with_or_without_intercept [2021/11/10 20:19] – Wolfgang Viechtbauertips:models_with_or_without_intercept [2024/06/12 17:45] – Wolfgang Viechtbauer
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 Now we will fit the model, but remove the intercept, which can be done with: Now we will fit the model, but remove the intercept, which can be done with:
 <code rsplus> <code rsplus>
-res <- rma(yi, vi, mods = ~ factor(alloc) - 1, data=dat)+res <- rma(yi, vi, mods = ~ 0 + factor(alloc), data=dat)
 res res
 </code> </code>
 +Alternatively, one could use ''mods = ~ factor(alloc) - 1'' to remove the intercept. In either case, the output is then:
 <code output> <code output>
 Mixed-Effects Model (k = 13; tau^2 estimator: REML) Mixed-Effects Model (k = 13; tau^2 estimator: REML)
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    estimate     se    zval   pval    estimate     se    zval   pval
 1:  -0.5180 0.4412 -1.1740 0.2404 1:  -0.5180 0.4412 -1.1740 0.2404
-2:  -0.9658 0.2672 -3.6138 0.0003+2:  -0.9658 0.2672 -3.6138 0.0003 ***
 3:  -0.4289 0.3449 -1.2434 0.2137 3:  -0.4289 0.3449 -1.2434 0.2137
  
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 </code> </code>
 <code output> <code output>
-Hypotheses:                                                          +Hypotheses: 
-1:     -factor(alloc)alternate + factor(alloc)random = 0  +1:     -factor(alloc)alternate + factor(alloc)random = 0 
-2: -factor(alloc)alternate + factor(alloc)systematic = 0  +2: -factor(alloc)alternate + factor(alloc)systematic = 0 
-3:    -factor(alloc)random + factor(alloc)systematic = 0 +3:    -factor(alloc)random + factor(alloc)systematic = 0
  
 Results: Results:
-   estimate     se    zval   pval  +   estimate     se    zval   pval 
-1:  -0.4478 0.5158 -0.8682 0.3853  +1:  -0.4478 0.5158 -0.8682 0.3853 
-2:   0.0890 0.5600  0.1590 0.8737 +2:   0.0890 0.5600  0.1590 0.8737
 3:   0.5369 0.4364  1.2303 0.2186 3:   0.5369 0.4364  1.2303 0.2186
 </code> </code>
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 Now what happens if we remove the intercept? Now what happens if we remove the intercept?
 <code rsplus> <code rsplus>
-res <- rma(yi, vi, mods = ~ ablat - 1, data=dat)+res <- rma(yi, vi, mods = ~ 0 + ablat, data=dat)
 </code> </code>
 <code output> <code output>
tips/models_with_or_without_intercept.txt · Last modified: 2024/06/18 19:29 by Wolfgang Viechtbauer