Variables
The list of variables is still under revision and definitions and descriptions will be further developed during the project. The list does not represent the variables that are to be collected in each case but the variables that are possible to collect in a case. A subset of these variables will be presented as “core” variables that are mandatory to collect for all teams. As the team becomes more experienced, it is the ambition that the teams collect more of the variables. However, a single case will never contain all variables as there are specific variables depending on the involved road users and the type of accident.
Notes are provided to describe individual variables. Help is also provided on how to collect the necessary information when investigating accidents. The wiki is intended to be a growing source of information and more variables will be defined and more help provided as the project develops. It is also a tool for future workers to continue adding and refining information after the DaCoTA project.
This list of variables is not intended to be a complete manual on how to investigate road accidents. Variable notes must be read together with notes elsewhere in this wiki, and alongside other methodological guidelines and experiences to be gained in training and from shared experiences with other experienced accident investigators.
Categories are provided to help locate related variables. However, please note that related variables are best identified by viewing the relevant areas of the DaCoTA on-line database system where related variables are grouped together on data-entry screens. Active links are also provided from the database to the variable descriptions in this wiki.
Within the DaCoTA - project there are a very large number of variables containing a wide variety of information which makes it impractical to set one common standard for when variables should considered as confident or should be coded as unknown. A few guidelines is however needed
- A variable value should never be coded solely on hearsay, rumours or an investigators hunch.
- A variable value should never be coded solely based on what is probable, i.e. code the driver as sleepy in DREAM as the accident occurred during the night.
- Some variables will always be based on the subjective judgement of an investigator, e.g. Restricted Sightline, Along Path (1476), as it is no definite line between yes and no in reality. As the investigator(s) on scene has the most information about the scene they are probably the best person to decide. Taking photos an extra photo in tricky cases can help both decision-making back at the office and future analyst to make up their own mind.
- For variables that are not confirmed Unknown should always be coded
- Not applicable should only be used when a variable is not valid, e.g. snow clearance status can be set to Not applicable if there is now possibility that there has been any snow to clear.
- Other is used when there is something to record but a suitable value is missing, e.g. a collision with a statue would be classified as other in collision objects. When other is used it is very important to use the commenting function in the system to explain what is meant.
- Unknown can also be used for variables that are confidential. E.g. some teams may not have the possibility to share certain information in the system and thus must code that information as Unknown.
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