sysuse auto.dta,clear

//r-class and e-class commands
//r-class commands r()

//Summarize command
sum mpg
return list
display r(max)
gen maxvar=r(max)
display r(max)-r(min)


//Summarize detail
sum mpg,detail
return list

//ttest 
ttest price , by(foreign)
return list
display `r(mu_1)'-`r(mu_2)'
display (`r(mu_1)'-`r(mu_2)')/r(se)

//e-class commands e() 
regress price mpg rep78

//scalar
ereturn list
scalar rsquare=e(mss)/(e(mss)+e(rss))
display rsquare


//function
sum if e(sample)==1
gen sample=e(sample)



//martix

//Getting values from matrix
matrix list e(b)
display e(b)[1,1]
scalar bmpg=e(b)[1,1]

matrix list e(V)
display sqrt(e(V)[1,1])

display e(b)[1,1]/sqrt(e(V)[1,1])

//simple method of accessing regression coefficients

display _b[mpg]
display _b[_cons]

display _b[_cons] + _b[mpg]*20 + _b[rep78]*3

display _se[mpg]

display _b[mpg]/_se[mpg]




return list
matrix list r(table)
display r(table)[3,1]
display _t[mpg]