Dimension
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A dimension is a means of summarising information by grouping it into sets. Dimensions describe their constituent sets consistently and efficiently, and therefore provide an ideal approach to analysing large amounts of data.
MAST dimensions are used to process raw data into measures stored in data cubes, so a large amount of information is readily available to users. They are also exposed for use as categories, series and filters in MAST reports.
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Dimension Structure - Hierarchies
A dimension consists of at heast one hierarchy. Each hierarchy defines a relevant way of organising information. Some hierarchies (for example Age and Geography) can apply to more than one dimension.
A hierarchy is organised into a structure of several levels, each containing a collection of sets. Hierarchies are organised in a similar way to family trees, so every set at each level is grouped within one of those at the level above. They generally have a single top level set, which includes all items in all the levels and categories beneath it.
Most MAST dimensions contain only one hierarchy, but some contain more if there are different ways in which that dimension's data could meaningfully be organised. Examples of this include the Conditions - Light and Conditions - Weather dimensions.
Example of a Hierarchy
Dimensions in MAST
MAST uses dimensions as a way of organising road safety and demographic data.
Sometimes the same dimension can apply to more than one variety of data. For example, crash, vehicle and casualty reports can all be summarised using the Crash Date dimension.
Other dimensions commonly used in MAST include:
- Dimensions based on the Geography hierarchy, which can apply to:
- Locations where crashes occur (Crash Location)
- Communities where involved drivers reside (Driver Home)
- Communities where casualties reside (Casualty Home)
- Dimensions based on the Severity hierarchy, which can be applied both to casualties and to crashes
- Dimensions based on Mosaic classification, which can apply to:
- Profiles of the communities where involved drivers reside (Driver Mosaic)
- Profiles of the communities where casualties reside (Casualty Mosaic)
- Dimensions based on the Age and Gender hierarchies, which can apply to both casualties and involved drivers
- Vehicle Type
