Hi,

I am trying to run an IV regression with internal instruments only (as per Lewbel 2012). My equation is specified as:

ivreg2h sf36mh (disab_psych=) retiree_type1 retiree_type3 age agesq ///
female partnered fem_part fem_type ///
household_size dependants ///
swave4 swave5 swave6 swave7 swave8 swave9 swave10 swave11 swave12 swave13 swave14 ///
swave15 swave16 swave17 swave18, rob first endogtest(disab_psych) fe

I get a warning that my variables have been centered (and they are 'forever changed' in the data). Why is this happening and can I stop this?

Thanks.