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| Data about data. | Stata offers human-readable variable names, variable labels, variable printing formats, and value labels. Stata stores variable labels and value labels in a separate database. Many built-in commands seamlessly pull in metadata from that database, but there are notable exceptions. <<TableOfContents>> ---- == Variable Names == Variables are (re)named using the `rename` command. Since Stata 12, it offers some advanced features: {{{ // rename all variables with a leading 'v' such that the 'v' is replaced with a 'V' rename v* V* // rename all variables with a leading 'new_' such that the prefix is stripped rename new_* * // rename all variables to a lowercase name rename *, lower }}} For older versions of Stata, try these: {{{ renpfix v V renpfix new_ // TODO: how did older versions rename variable to lowercase? }}} ---- == Labels == === Variable Labels === Variable labels are defined using the '''`label`''' command. {{{ label variable VAR "var" }}} Variable metadata including labels can be inspected and exported using the '''`describe`''' command. {{{ preserve describe, replace assert varlab=="foo" if name=="bar" restore }}} === Value Labels === Variable labels are defined using the '''`label`''' command. However, they must first be defined as a label and then linked to one or more variables. {{{ label define LABEL 0 "No" 1 "Yes" label define LABEL 99 "Missing", modify label values VAR LABEL }}} By default, labels cannot be overwritten. The '''add''' option allows new values to be inserted into an existing label. The '''replace''' option allows existing values to be overwritten in an existing label. The '''modify''' option combines both. Numeric values can be added to value labels using the '''numlabel''' command. {{{ numlabel LABEL, add mask("#. ") }}} |
Stata Metadata
Stata offers human-readable variable names, variable labels, variable printing formats, and value labels.
Stata stores variable labels and value labels in a separate database. Many built-in commands seamlessly pull in metadata from that database, but there are notable exceptions.
Variable Names
Variables are (re)named using the rename command. Since Stata 12, it offers some advanced features:
// rename all variables with a leading 'v' such that the 'v' is replaced with a 'V' rename v* V* // rename all variables with a leading 'new_' such that the prefix is stripped rename new_* * // rename all variables to a lowercase name rename *, lower
For older versions of Stata, try these:
renpfix v V renpfix new_ // TODO: how did older versions rename variable to lowercase?
Labels
Variable Labels
Variable labels are defined using the label command.
label variable VAR "var"
Variable metadata including labels can be inspected and exported using the describe command.
preserve describe, replace assert varlab=="foo" if name=="bar" restore
Value Labels
Variable labels are defined using the label command. However, they must first be defined as a label and then linked to one or more variables.
label define LABEL 0 "No" 1 "Yes" label define LABEL 99 "Missing", modify label values VAR LABEL
By default, labels cannot be overwritten. The add option allows new values to be inserted into an existing label. The replace option allows existing values to be overwritten in an existing label. The modify option combines both.
Numeric values can be added to value labels using the numlabel command.
numlabel LABEL, add mask("#. ")
Quick Tips
Stata has a number of interactive tools for examining metadata.
di _N // number of cases di c(k) // number of variables