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Describes the time dimension of the data collection.
| Value of the Code | Descriptive Term of the Code | Definition of the Code |
|---|---|---|
| Longitudinal | Longitudinal | Data collected repeatedly over time to study change in a population. |
| Longitudinal.CohortEventBased | Longitudinal: Cohort/Event-based | Data collected over time about a group of individuals that are connected in some way or have shared some significant experience within a given period. Examples: birth, disease, education, employment, family formation, participation in an event. |
| Longitudinal.TrendRepeatedCrossSection | Longitudinal: Trend/Repeated cross-section | Studies different samples/different groups of people from the same population at several points in time, using the same set of questions/variables. Conclusions are drawn for the population. Examples: public opinion polls, elections studies, etc. |
| Longitudinal.Panel | Longitudinal: Panel | Data collected over time from, or about, the same sample of respondents. |
| Longitudinal.Panel.Continuous | Longitudinal: Panel: Continuous | Reports from the panel are collected on a regular basis. |
| Longitudinal.Panel.Interval | Longitudinal: Panel: Interval | Measurements are taken only when information is needed. |
| TimeSeries | Time Series | Data collected repeatedly over time to study change in observations. These are typically "objective" measurements of phenomena that can be observed externally, as opposed to attitudes/opinions or feelings. Examples may include economic/financial indicators, natural/meteorological phenomena, vital statistics, etc. |
| TimeSeries.Continuous | TimeSeries: Continuous | Phenomena are measured at every instant in time. Examples: lie detectors, electrocardiograms, etc. |
| TimeSeries.Discrete | TimeSeries: Discrete | Measurements are taken at (usually regularly) spaced intervals. Examples: macroeconomics (weekly share prices, monthly profits, sales); meteorology (hourly temperature); measurements of individuals (blood pressure, weight, height); sociology (crime figures, employment figures), etc. |
| CrossSection | Cross-section | Cross-sectional data is data collected by observing subjects at the same point in time, or without regard to differences in time. Analysis of cross-sectional data usually consists in comparing the differences among subjects, but is not focused on studying change over time (adapted from Wikipedia). |
| CrossSectionAdHocFollowUp | Cross-section ad-hoc follow-up | Data collected at one point in time to complete information collected in a previous cross-sectional study; the decision to collect follow-up data is not included in the study design. |
| Other | Other | Use if the time method is known, but not found in the list. |
The element TimeMethod is a string type in DDI 3.1, but will be changed to CodeValueType in DDI 3.2. Controlled vocabulary codes can still be used with this element in DDI 3.1, but it will not be possible to reference the external controlled vocabulary by using the attributes created for this purpose in CodeValueType.
| Module Name | Element Name |
|---|---|
| datacollection | TimeMethod |
| Element Number | Element/Attribute Name |
|---|---|
| 2.3.1.1 | timeMeth@method |
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