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Guidance in this section will be used with detailed guidance in Section 2.7.6, Metadata for Individual Health to implement collection standards.

Collection of Dates

Collect dates in such a way as to allow sites to record only the precision they know. The system should also store only the collected precision. Any incomplete dates must remain incomplete with no imputation and no “zero-filling” of missing components. Data collection and database processes should allow for the possibility of partial dates and times, because a partial date may be the most precise information that can be collected for some data. 

If a full date is collected (or expected), the CDASH variable --DAT or all 3 date components (i.e., --DATYY, --DATMO, --DATDD) should be included on the collection tool. If a partial date can be collected in a single field, the CDASH --DAT should be used. If a partial date must be collected as separate database fields to collect year, month, and day, refer to the CDASH Model for examples of standard naming fragments (--YY, --MO, --DD, --TIM). The capabilities of individual software systems (e.g., EDC) will determine which variable names are needed. CDASH uses separate data collection fields for dates and times. 

Imputation of Dates

The visit date variable (VISDAT) can be applied to all observations for a given visit (if appropriate), or specific date and timing fields may be included for a specific observation in the body of the CRF. When the visit date is used to reflect the timing of an observation, the appropriate timing variable for that tabulation dataset may be populated with the CDASH Visit Date.