Adjusting Date Format

[Gary Hammersmite]

Hello,

Could anyone help with a command that takes my year variable in the format "xxxx-xx" and changes it into the format of "xxxx-xxxx". For example if I have "2016-17" I would want to change it to "2016-2017". Thank you.

[Nick Cox]

You haven't said what is the earliest case you have. This assumes that you may have some 20th century examples.

clear 
input str7 twoyear 
"1998-99"
"1999-00"
"2001-02"
"2022-23"
end 

gen wanted = subinstr(twoyear, "-", "-19", 1) if real(substr(twoyear, 1, 4)) <= 1998 
replace wanted = subinstr(twoyear, "-", "-20", 1) if real(substr(twoyear, 1, 4)) >= 1999

list 

     +---------------------+
     | twoyear      wanted |
     |---------------------|
  1. | 1998-99   1998-1999 |
  2. | 1999-00   1999-2000 |
  3. | 2001-02   2001-2002 |
  4. | 2022-23   2022-2023 |
     +---------------------+

If all the years are from this century then

gen wanted = subinstr(twoyear, "-", "-20", 1)

should suffice.

For most purposes I would want to hold the years as single integers and use value labels for display.