/* Work problem similar to the one on p. 20 */

log using "SOCY602-GSS-Sociability-Percentile-Example.txt", replace text

quietly {
  sum sociability if year==2006
  local lb=r(mean) - invnormal(.95)*(r(sd)/(r(N)^.5))
  local ub=r(mean) + invnormal(.95)*(r(sd)/(r(N)^.5))
  noisily di _n  _col(2) "Lower bound = " %6.2f `lb'
  noisily di     _col(2) "mean        = " %6.2f r(mean)
  noisily di     _col(2) "Upper bound = " %6.2f `ub'
}


/* Solve using Stata's built-in function */
ci sociability if year==2006

log close