[R] Using lm's subset parameter results in Error in xj[i] : invalid subscript type 'list'

[Jorge Cimentada]

By subsetting the rows in the firstkids data frame, you've already
subsetted your data.

Try specifying firstkids as your data instead of a subset in the lm call.
Also, eliminate the kidmomhsage prefix from all of your variables since
you're running the linear model on a different data frame(firstkids)

Something along this line:

lm(kid_score ~ mom_age ...., data = firstkids)

*Jorge Cimentada*
*Ph.D. Candidate*
Dpt. Ciències Polítiques i Socials
Ramon Trias Fargas, 25-27 | 08005 Barcelona

Office 24.331
[Tel.] 697 382 009
jorge.cimentada at upf.edu
http://www.upf.edu/dcpis/



On Tue, Sep 20, 2016 at 10:00 AM, mviljamaa <mviljamaa at kapsi.fi> wrote:

> I'm trying to take lm on a subset of my dataset and to do this I believe I
> need to pass my subset of the data as the subset parameter of lm.
>
> So I do my subsetting:
>
> firstkids <- kidmomhsage[0:234,], i.e. the first 234 rows of the data
> frame.
>
> Then construct the model:
>
> fit4 <- lm(kidmomhsage$kid_score ~ kidmomhsage$mom_age +
> kidmomhsage$mom_hs + kidmomhsage$mom_age * kidmomhsage$mom_hs,
> subset=firstkids)
>
> which results in:
>
> Error in xj[i] : invalid subscript type 'list'
>
> I read somewhere a recommendation to use "unlist":
>
> fit4 <- lm(kidmomhsage$kid_score ~ kidmomhsage$mom_age +
> kidmomhsage$mom_hs + kidmomhsage$mom_age * kidmomhsage$mom_hs,
> subset=unlist(firstkids))
>
> which seems to not produce the error and results in some sort of model,
> but is this model the correct one (i.e. for the data set firstkids, just as
> it originally appears)? How does unlist change the data?
>
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