The tabulate command requires a varname see tabulate oneway. A varname refers to exactly one variable. Some commands take a varname, rather than a varlist. In commands that alter or destroy data, Stata requires that the varlist be specified explicitly. What does Varlist required mean in Stata? After a preserve, the programmer can also instruct Stata to restore the data now with the restore command. When the program or do-file concludes, the user's data are automatically restored. When preserve is issued, the user's data are preserved. Possible solutions include adding more memory to your computer or moving to a 64-bit machine. A clear indicator is constant, prolonged disk access during the execution of a command. Why is Stata running very slowly? Stata is using more memory than is physically available on your computer. There are two special values, written null and undefined, that are used to denote the absence of a meaningful value. Is used to signify absence of value evaluating to false in a situation? Spending a little time learning the syntax itself will make it much easier to use commands later. Stata tries very hard to make all its commands work the same way. What is the difference between and = in Stata?
The first version was released in 1985 with 44 commands. Stata was written, then as now, in the C programming language, initially for PCs running the DOS operating system. Related guide for Can You Use If In Stata? What coding language does Stata use?
On debugging: Stata will stop with an error message as soon as it hits a problem. In your examples, possibly year is a string variable somehow. What is a type mismatch error in Stata?Ī type mismatch means that you trying to do something numeric to strings, or vice versa. It is sometimes called logical equals because it is part of a logical test that returns either a one (true) or a zero (false). The double equals, =, is used to test for equality.