sysuse auto, clear

foreach var of varlist price mpg {
    xtile high_`var' = `var', nq(2)
    replace high_`var'=high_`var'-1
    table high_`var', c(mean `var' min `var' max `var')
}

reg foreign i.high_price i.high_mpg weight, robust
test 1.high_price=1.high_mpg
lincom 1.high_price-1.high_mpg