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High Impact / Low Probability Analysis

Assume an unlikely outcome has happened and determine its impacts.


High Impact / Low Probability Analysis is used to raise awareness of the major impacts from an unlikely outcome. This technique is helpful when unanticipated developments suggest that a “long-shot” scenario has become more likely.

To perform a High Impact / Low Probability Analysis:

Step 1:  Assume that one of your outcomes has already occurred.

Step 2:  Clearly define what happened and its impact. Was there a trigger event? Were there secondary impacts?

Step 3:  Identify the recent information that may suggest an increased likelihood of this outcome.

Step 4:  Develop a logical chain of argumentation to explain how this could have happened. Extrapolate from current information and project out to your potential outcome.

Step 5:  Map out any other credible ways this outcome could have happened.

Step 6:  Generate a list of Indicators that can provide you with an early warning system that this outcome may be unfolding.

Step 7:  Assess the impact of negative scenarios. Develop contingency plans to overcome these difficulties.

Step 8:  Assess the impact of positive scenarios. How could these be enabled?

Step 9:  Monitor your indicators.

Publications icon


Handbook of Analytic Tools and Techniques, Randolph H. Pherson, Reston, VA: Pherson Associates, 2008.

Structured Analytic Techniques for Intelligence Analysis, Richards Heuer, Jr. and Randolph H. Pherson, Washington DC: CQ Press, 2011.