[R-meta] Fwd: About the coefficient in meta-regression analysis

Dear Michael and all,

        Thank you for the swift response. I do have some further questions
to ask.
        (a) So, in order to "remove" the intercept, what code should I use?

        (b) Let's say my research is about whether using digital games will
affect the result of English vocabulary acquisition or not. So as you said,
"... remove the intercept so each coefficient would then be tested for its
difference from zero." , does that mean if I rerun the code again with the
removal of intercept and presumably get an estimate of 0.3 from the
subgroup "eduH" and the p-value is less than 0.05. Can I say that "eduH has
a positive coefficient to English vocabulary acquisition"? If not, what
would the coefficient mean here (since there is no intercept to compare to)?

      Thanks again for your kindly help!
     Nick
??? (Nick Chen)
Email: t571 at wlgsh.tp.edu.tw <t5741 at wlgsh.tp.edu.tw>


Michael Dewey <lists at dewey.myzen.co.uk> ? 2023?12?19? ?? ??9:14???

Dear Nick

Comments in line

On 19/12/2023 11:51, ?????? via R-sig-meta-analysis wrote:

Dear all,
         This is part of my meta-regression analysis result after I use

the

following code:

m.gen.edu <- metareg(m.gen, ~edu)

      Model results:
                                 estimate  .....
intercept                0.6820   .....
eduH                      0.4590   ......
eduI                        -0.0834 ......
eduK                       0.5668 ........
eduS                       0.2473   .......

       The *edu *here stands for the moderator "educational level" from my
dataset and the *eduH, eduI, eduK*, and *eduS* stands for different
subgroups. Does the 0.4590 here represent the coefficient of the subgroup
*eduH* ?

In a model with an intercept each level is compared to a reference level
so the value, 0.4590, is the difference estimated between group H and
the reference group.

   And is there a code to get the overall coefficient of the

moderator "educational level" rather than the individual coefficient of
each subgroup?

The short answer is "No". You can do a test for the overall effect of
educational level. You could also in a simple model like this remove the
intercept so each coefficient would then be tested for its difference
from zero.

Michael

   Nick Chen

??? (Nick Chen)
Email: t571 at wlgsh.tp.edu.tw <t5741 at wlgsh.tp.edu.tw>

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--
Michael

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