Export Variables¶
Variable Types¶
| Type | format | comments/associated REDCap metadata |
|---|---|---|
| INTEGER | REDCap field type slider or REDCap field validation integer |
|
| FLOAT | w.d as determined by PHP | REDCap field type calc or REDCap field validation float. 14 significant digits (IEEE 64-bit). |
| DATE | yyyy-mm-dd | REDCap field validations date_mdy, date_ymd, date_dmy, date_dmy |
| DATETIME | yyyy-mm-dd hh:nn:ss | REDCap field validations datetime_mdy, datetime_ymd, datetime_dmy, datetime_seconds_mdy, datetime_seconds_ymd, datetime_seconds_dmy |
| TIME | hh:nn:ss | REDCap field validation time |
| NOMINAL | value set | REDCap field types radio, yesno, truefalse, select (dropdown) |
| CHECKBOX | value set | REDCap field type checkbox |
| TEXT | REDCap field type paragraph/notes, REDCap field type sql or REDCap field type text with no REDCap field validation |
CHECKBOX data values: If a "check all that apply" checkbox has multiple items, they will be returned in the export data as a comma-separated list of checked values. This is equivalent to the
combine_checkbox_valuesoption of the REDCap::getData() method.
REDCap Attribute variables¶
Depending on the export layout and study design, an exported dataset may include one or more "REDCap Attribute" variables. These are the intrinsic REDCap attributes that may be associated with an output record: data access group, event and instance. Where possible we have used the same names that are used by the REDCap API. The full list is shown below.
| variable name | type | example |
|---|---|---|
| redcap_data_access_group_id | INTEGER | 31 |
| redcap_data_access_group_name | TEXT | utmb |
| redcap_event_id | INTEGER | 4159 |
| redcap_event_name | TEXT | baseline_arm_1 |
| redcap_repeat_instance | INTEGER | 1 |
REDCap Data variables¶
All exported datasets include REDCap data values of course, and these are stored in REDCap Data variables. For vertical and repeated export layouts, the variable names for REDCap data will be the same as the underlying REDCap field_name. For horizontal layouts the variable names will be composites of the REDCap event prefix and the REDCap field name.
Work with REDCap project designers to ensure that for longitudinbal studies the length of no composite field name exceeds the limits imposed by any statistical packages that will be used to process the exports.
For example, the variable name limit for SAS and STATA is 32 characters, for MATLAB the limit is 63 characters and for R the limit is 64 characters. You should be okay, even considering the event prefixes, if field names adhere to the length warnings broadcast by the REDCap Field Editor.