[R-sig-ME] Help with interpreting one fixed-effect coefficient

[Juho Kristian Ruohonen]

Fellow student commenting here...

As you suggest, schgendgirl-only can only ever apply to female students.
Strictly speaking, it's the estimated mean difference between a student of
any sex in a girls-only school and a similar student in a mixed school. But
since such comparisons are only observed between girls, the estimate is
necessarily informed by girl data only. So your intended interpretation of
the coefficient is correct.


su 26. syysk. 2021 klo 0.27 Simon Harmel (sim.harmel using gmail.com) kirjoitti:

> Dear Colleagues,
>
> Apologies for crossposting (
> https://stats.stackexchange.com/q/545975/284623).
>
> I've two categorical moderators i.e., students' ***sex*** (`boys`,
> `girls`) and the ***school-gender system*** (`boy-only`, `girl-only`,
> `mixed`) in a model like: `y ~ sex + schoolgend`.
>
> My coefs are below. I can interpret three of the coefs but wonder how
> to interpret the third one from the top (.175)?
>
> Assume "intrcpt" represents the boys' mean in mixed schools.
>
>                          Estimate
> (Intercept)             -0.189
> schgendboy-only   0.180
> schgendgirl-only    0.175
> sexgirls                  0.168
>
> My interpretations of the coefficients are as follows:
>
>             "(Intercept)": mean of y for boys in mixed schools = -.189
>  "schgendboy-only": diff. bet. boys in boy-only vs. mixed schools = +.180
>   "schgendgirl-only": diff. bet. ???????????????????????????? = +.175
>                 "sexgirls": diff. bet. girls vs. boys in mixed schools =
> +.168
>
> If my interpretation logic for all other coefs is correct, then, this
> third coef. must mean:
>
> diff. bet. boys in girl-only vs. mixed schools = +.175! (which makes no
> sense!)
>
> ps. I know I will end-up interpreting +1.75 as: diff. bet. girls in
> girl-only vs. mixed schools BUT this doesn't follow the interpretation
> logic for other coefs PLUS there are no labels in the output to show
> what's what!
>
> Many thanks,
> Simon
>
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