Variables are the units in which Lifelinesdata are organized.

Each variable has a name that looks like a code:

keyword1_keyword2_subjectcode_type_number_specification

• Keyword1 describes the most important attribute of the variable. In many cases, it describes the measurement (i.e. ecg) or the validated questionnaire (i.e. ctq) that was performed.
• Keyword2 gives more detailed information about the variable. Since each variable code must be unique, this keyword helps to distinguish between two similar variables.
• The subjectcode describes the type of participant that was the subject of the variable. See table below for an overview
• The type describes whether the variable is a question, a measurement etc. See table below for an overview.
• The number shows the order in which the variable is placed relative to other similar variables. In case of validated questionnaires, the number corresponds to the number of the question in the original instrument.
• The specification could be a letter (in case of specifications for an earlier main question) or a number (in case of repeated questions for, for example, multiple unnamed sports, diseases, or medications)