GRRM/How To/LevelOfCertainty
Applying the Methodology to Geothermal Projects
Level of Certainty
In reporting methdologies, certainty is traditionally determined in two ways:
Deterministic scenarios - a discrete estimate of the certainty of a single scenario within a range of possible outcomes determined by an analyst.
- Differences in scenarios are primarily based on the analyst’s projections. The analysts determine whether currently available data correspond to separate, distinct scenarios in order to represent three situations: reasonably certain, more likely than not, and unlikely.
(e.g. a single outcome of a decision tree)
Probabilistic distributions - a wide range of confidence levels derived from iterations of varying scenarios.
- Differences in scenarios are based on repeated randomized sampling.
(e.g. Monte Carlo results)
The following table provides the details to select the appropriate level of certainty associated with the confidence in estimates of geothermal resource potential:
Options to Describe Level of Certainty
Certainty | Probabilistic Outcomes | Deterministic Scenarios |
Low | P_{10}: there is an estimated 10% probability that the correct answer will lie between 0 and P_{10} | Unlikely: Low degree of confidence that actual value will be at least X amount |
Mean | P_{50}: there is an estimated 50% probability that the correct answer will lie between 0 and P_{50} | More likely than not: Equal degree of confidence and uncertainty that actual value will be at least X amount |
High | P_{90}: there is an estimated 90% probability that the correct answer will lie between 0 and P_{90} | High degree of confidence that actual value will be at least X amount |