Mplus Users Guide v6.. - Muthén & Muthén

CHAPTER 15THE DEFINE COMMANDDEFINE:The DEFINE command is used to transform existing variables and createnew variables. It contains a special function for categorizing continuousvariables. The operations available in DEFINE can be executed for allobservations or selectively using conditional statements.Transformations of existing variables do not affect the original data butonly the data used for the analysis. If analysis data are saved using theSAVEDATA command, the transformed values rather than the originalvalues are saved.The statements in the DEFINE command are executed one observationat a time in the order found in DEFINE. Any variable listed in theNAMES option of the VARIABLE command or previously created inDEFINE can be transformed or used to create new variables. Newvariables created in DEFINE that will be used in an analysis must belisted on the USEVARIABLES list after the original variables that willbe used in the analysis.Following are examples of the types of transformations available:variable = mathematical expression;IF (conditional statement) THEN transformationstatements;variable = MEAN (list of variables);variable = CLUSTER_MEAN (variable);variable = SUM (list of variables);CUT variable or list of variables (cutpoints);_MISSINGDEFINE is not a required command.512