How do I find the summary statistics of top 50 richest countries in a 100 country dataset

[Shashank Shukla]

I want to determine the mean, standard deviation etc. for the top 50 countries by GDP in a 100 country dataset. I have sorted in descending order using gsort command but unable to figure how to find mean for the top 50.
I can always use the crude way of visually looking at the 51st country and then using the "if {var} > {value} but I am sure there must something more elegant in STATA

[Jared Greathouse]

Look up egen's "rank" function. Note that if you have panel data, countries may not have the same rank year by year

[Clyde Schechter]

Assuming that you are not dealing with panel data:

sysuse auto, clear

gsort -price
// DESCRIPTIVE STATISTICS FOR 50 MOST EXPENSIVE CARS
summ price mpg headroom in 1/50

illustrates the approach.