help ckkeep, help ckdrop
-------------------------------------------------------------------------------

Title

    ckkeep - Keep variables without losing validation
 

        ckkeep varlist, [stubs(char stubs) listonly]

        ckdrop varlist, [stubs(char stubs) listonly]

Description

    These functions replace keep and drop, when using attached
    characteristics for validation. Using these functions ensure that
    variables needed for validation or scoring of the kept variables are not
    mistakenly dropped.

Options

INCLUDE help ckcharstub

    listonly does not go through dropping any variables. It simply compiles a
        list of what variables would be left over if the command were
        actually run.

Also see

    Online: help for keep, ckvar overview, ckchar

 Author

    Bill Rising, StataCorp
    email: brising@stata.com
    web: http://homepage.mac.com/brising