Speaking Stata: How best to generate indicator or dummy variables

Indicator or dummy variables record whether some condition is true or false in each observation by a value of 1 or 0. Values may also be missing if truth or falsity is not known, and that fact should be flagged. Such indicators may be created on the fly by using factor-variable notation. tabulate also offers one method for automating the generation of indicators. In this column, we discuss in detail how otherwise to best generate such variables directly, with comments here and there on what not to do.

指示变量（Indicator variables）或虚拟变量（dummy variables）通过取值1或0来记录每个观测中某一条件是否成立。若无法确定条件的真假，变量值可能缺失，且该情况需标记。此类指示变量可通过因子变量符号（factor-variable notation）即时生成。tabulate函数也提供了一种自动化生成指示变量的方法。本专栏将详细探讨如何以其他方式直接生成此类变量，并穿插说明应避免的操作。