sysuse auto
eststo: quietly regress price weight mpg
matrix bstdy = e(b)
quietly summarize price if e(sample)
matrix bstdy = bstdy / r(sd)
estadd matrix bstdy = bstdy
eststo: quietly regress price weight mpg foreign
matrix bstdy = e(b)
quietly summarize price if e(sample)
matrix bstdy = bstdy / r(sd)
estadd matrix bstdy = bstdy
estout, cells(b bstdy(par)) 
eststo clear