Family Fixed Effects with large number of fixed effects

[Lindsey Buck]

Hi Everyone,

I am trying to run family fixed effects. I have a ton of mother ids to identifiy where kids are coming from, and I want to run
reg y x i.momid

But I keep getting an error that says I have "too many variables specified."
I tried doing xtset and xtreg and I also tried reghdfe and none of these worked (or maybe I didn't use them right). I have a cross section of data that record's a mother's id and some variables about her children. Can you assist?

[Andrew Musau]

reghdfe is from SSC as you are asked to explain. Different ways:

reg y x, a(momid)
areg y x, a(momid)
reghdfe y x, a(momid)
xtset momid
xtreg y x, fe