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| Terms |
Definitions |
| Behavioural variability |
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| Bias |
A constant or systematic deviation as opposed to a random error.
It appears as a persistent over- or under-estimation of the quantity measured, calculated or estimated.
See also expert bias and value loading. |
| Bias: Anchoring |
Assessments are often unduly weighted
toward the conventional value, or first value given, or to the
findings of previous assessments in making an assessment.
Thus, they are said to be 'anchored' to this value. |
| Bias: Availability |
his bias refers to the tendency to give too
much weight to readily available data or recent experience
(which may not be representative of the required data) in
making assessments. |
| Bias: Coherence |
Events are considered more likely when many
scenarios can be created that lead to the event, or if some
scenarios are particularly coherent. Conversely, events are
considered unlikely when scenarios can not be imagined.
Thus, probabilities tend to be assigned more on the basis of
one's ability to tell coherent stories than on the basis of
intrinsic probability of occurrence. |
| Bias: Overconfidence |
Experts tend to over-estimate their
ability to make quantitative judgements.
This can sometimes be seen when an estimate of a quantity and
its uncertainty are given, and it is retrospectively discovered that
the true value of the quantity lies outside the interval.
This is difficult for an individual to guard against;
but a general awareness of the tendency can be important. |
| Bias: Representativeness |
This is the tendency to place more
confidence in a single piece of information that is
considered representative of a process than in a larger body
of more generalized information. |
| Bias: Satisficing |
this refers to a common tendency to search through a limited
number of familiar solution options and to pick from among them. Comprehensiveness is sacrificed for expediency in
this case. |
| Bias: Unstated assumptions |
A subject's responses are
typically conditional on various unstated assumptions. The
effect of these assumptions is often to constrain the degree
of uncertainty reflected in the resulting estimate of a
quantity. Stating assumptions explicitly can help reflect
more of a subject's total uncertainty. |
| Burden of proof |
The `burden of proof' sets the onus of responsibility
in argumentation according to whether one must prove positive or negative attributes (innocence/guilt; presence/absence, etc.) about the issue in dispute. The burden of proof therefore sets out who is responsible for making a case. For example, burden of proof in
environmental regulation may be set such that an activity will not be regulated or prohibited unless proof of harm can be made. Alternatively, the burden of proof may be set such that activities of a certain kind will be prohibited unless it can be proved that they will do no harm. |
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