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Types of Evaluation Criteria: A Summary |
Generally, proxies tend to be overused, so be on guard. But they
can also be extremely useful. A practical approach
involves:
- Use proxies at the scoping stage (they are generally much
easier to estimate than the corresponding natural
criteria).
- Based on preliminary analysis, eliminate, if possible,
some proxies from further consideration (because they are
insensitive to the alternatives for example, or closely
correlated with another criterion).
- Be explicit about the range of possible and/or presumed
relationships between the proxy and the
endpoint/objective.
- When using one proxy to represent multiple objectives,
make sure there are no hidden trade-offs.
- If trade-offs involving a proxy are pivotal to the
decision, use a structured expert judgment process to better
understand the relationship of the proxy to the
endpoint/objective.
Conclusion
- Use conceptual models such as influence diagrams to help
identify appropriate criteria and focus information
gathering and model building efforts.
- Use natural criteria if you can. Consider expert judgment
to estimate them if modeling is not available.
- Use constructed scales as a second choice. If they are
carefully constructed, they are surprisingly
effective.
- Use proxies freely at the scoping stage. Use them
cautiously at later stages if they are key to final choices
about difficult trade-offs. They are surprisingly
problematic.
- There are no right or wrong criteria, but there are good
ones and bad ones. Know the limitations of the criteria you
use.
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Key Ideas |
Be cautious when using proxies: there are a number of
pitfalls associated with them
Natural attributes make the best evaluation criteria,
followed by constructed attributes, and then proxies.
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