Difference between revisions of "Category:Dimension"

Revision as of 12:53, 9 September 2008

This page describes common and important dimensions in open assessments. For a description about the essence of dimensions and their operationalisations (indices), see Index.

Scope

Dimension is such a property that can have specific values or locations and that can be used to discretise or conditionalise variables or assessments along these locations. This page describes such dimensions that effectively categorise the content of any environmental health impact assessment.

To increase the usability of objects in open assessment, it is advisable to use uniform structures whenever possible. Also dimensions (and indices) should be uniform from one assessment to another as much as is practically possible. This page offers generally applicable dimensions.

What are dimensions that are

• important for fulfilling assessments,
• needed often in different kinds of assessments,
• general in nature so that they are applicable to a large number of assessment?

Definition

Each dimension should be useful for describing some important aspect of an assessment (or a part of an assessment).

Interpretation of a value

• An exact value for a particular location
• An integrated value (average or sum) for a range of locations

Locations for time

• Like other dimensions
• Current (the point in time that is described by the variable changes but is always unambiguously defined to the current time point)

Types of indices

• an arbitrary index
• a standardised index
• a continuous index

There are two kinds of dimensions.

• the variable has several values at the same time along the dimension (like a concentration field)
• the variable is about a random individual in a group (like body weight). The variable has a value for each individual, which can be classified along a dimension e.g. age. Not all age locations have observations, and there is not a requirement of continuity from one age point to another. However, if the variable is about the average body weight, it is continuous and has a value at evergy age point because then it is a prediction of the weight of a person of that age.

Developmental stages of variables

Result

These dimensions should be included for environmental health impact assessments:

• Activity sector
  • From economic classification of e.g. gross domestic product
• Emission source
  • How does this differ from economic classification? Probably more concrete.
• Pollutant
• Environmental compartment
• Exposure route
  • Food, drinking water, ingestion (non-food), breathing, dermal contact, sensory
• Health impact. It has at least two sub-dimensions:
• Non-health impact
• Decision
• Time
• Spatial location
• Person or group
• Species: Any animal or plant species. Used for food species as well as ecological assessments.
• Valuation: Any kind of list for different valuations. Especially useful for multiattribute utilities. This can have several sub-dimensions.
  • Cost type: A list for different valuations that can be expressed in monetary terms.

These are possibly not dimensions, but they are listed here until we understand what they are:

• Step: A particular location in a typical causal chain of an environmental health assessment.
• Sample: A discrete dimension for a random sample of values drawn from a probability distribution. It is a sequence of integers 1, 2, 3,...n, where n is the sample size. Within one model, all variable results for each location in sample must be coherent. In the result database, this dimension is described within the Result table, not in Location table as all others.