Dear,

I want to collapse the years into periods of, say, two years each. For example, if I have a panel from 1990 to 1995, I want period I = 1990-1991, period II = 1992-1993, and period III = 1993 & 1994. Within each period, I will then calculate the average (mean) or identify the mode for each variable.

How can I do that in Stata?

Let me give an example with the following made-up dataset:

input str10 country year x y
"Indonesia" 1990 24 36
"Indonesia" 1991 28 22
"Korea" 1990 38 27
"Korea" 1991 42 73
"China" 1990 124 458
"China" 1991 12 24
end

I want to collapse 1990 and 1991 into just one period, so the x-value for Indonesia would be (24 + 28)/2 and the corresponding y-value (36 + 22)/2.

Now, imagine I also have the row for years 1992-2021. That means I can't just do "collapse varlist, by (country)". I will first need to create a variable called "period" that takes the value = 1 for 1990 & 1991, = 2 for 1992 & 1993, and so on.

I could do that manually one by one, but there must be a smart way to do this in Stata.

Is it possible to get help?

Best,