Dates and time periods are managed using the ISO 8601 standard and, where relevant, SDMX conventions for reporting time dimensions. Two principal temporal concepts are used within the statistical data model: date_coverage and time_period.
Date coverage
Section titled “Date coverage”Date coverage refers to the period during which the underlying data were collected or the period to which the source data relate. Date coverage is normally represented through two fields:
date_coverage_startdate_coverage_end
Both fields are stored as complete dates using the format YYYY-MM-DD, regardless of the level of precision available from the source.
Examples:
| Scenario | date_coverage_start | date_coverage_end |
|---|---|---|
| Data collected from 10 March to 22 April 2024 | 2024-03-10 | 2024-04-22 |
| Data collected during March 2024 | 2024-03-01 | 2024-03-31 |
| Data collected during 2024 | 2024-01-01 | 2024-12-31 |
Time period
Section titled “Time period”Time period represents the point or period in time to which a statistic refers. It is the principal temporal dimension used for analysis, visualization and comparison across observations.
The level of temporal granularity depends on the nature of the statistic and its reporting frequency. For example, annual population statistics may be reported by year, while operational statistics may be reported by month, week or day.
Each time_period is accompanied by a corresponding format which identifies the temporal resolution being used.
Examples:
| Reference period | time_period | format |
|---|---|---|
| Year 2024 | 2024 | YYYY |
| First half of 2024 | 2024-H1 | YYYY-HH |
| Third quarter of 2024 | 2024-Q3 | YYYY-QQ |
| March 2024 | 2024-03 | YYYY-MM |
| Week 12 of 2024 | 2024-W12 | YYYY-WW |
| 15 March 2024 | 2024-03-15 | YYYY-MM-DD |
date_coverage and time_period serve different purposes. Date coverage describes the period covered by the source data, whereas time_period represents the temporal dimension against which the resulting statistic is reported and analysed.