ACH

Analysis of Competing Hypotheses (ACH) is an analytic process that identifies a complete set of alternative hypotheses, systematically evaluates data that is consistent and inconsistent with each hypothesis, and rejects hypotheses that contain too much inconsistent data. It is a simple model for how to think about a complex problem. The ACH methodology was developed by Richards J. Heuer, Jr.

The method for analyzing competing hypotheses takes time and attention in the initial stages, but pays big dividends in streamlining management and coordination of analytic positions. ACH is particularly useful for issues that require a careful weighing of alternative explanations of what has happened or is happening. It can also be used to provide early warning or to help you evaluate alternative scenarios of what might happen in the future.

ACH helps you overcome, or at least minimize, some of the cognitive limitations that make prescient intelligence analysis so difficult; it helps clarify why analysts are talking past one another and do not understand each other's interpretation of the data. ACH is grounded in basic insights from cognitive psychology, decision analysis, and the scientific method. It helps analysts protect themselves from avoidable error and improve their chances of making the right call.

You can download the ACH software tool from here. Click HERE if you would like to practice using the ACH tool. The following articles provide more information about ACH and its value for intelligence analysis:

• Overcoming Analytic Mindsets: Five Simple Techniques, by Randolph H. Pherson
• Improving Intelligence Analysis with ACH, by Richards J. Heuer, Jr.
• ACH: An Eight-Step Process
• ACH Tutorial, by Richards J. Heuer, Jr. and Randolph H. Pherson
• ACH Technical Description, Palo Alto Research Center

Pherson Associates is developing two simple, but elegant, web-enabled tools that will enhance the power of ACH. Click on each tool for a more detailed description.

Collaborative-ACH (C-ACH).

Pherson Associates, building on the analytic expertise of its senior managers and lessons learned from teaching the Analysis of Competing Hypotheses (ACH) methodology to over 2,500 IC analysts, has built a collaborative version of ACH that is now undergoing beta testing. C-ACH includes all the functionalities of ACH but adds a powerful tool to analyze the degree of disagreement among analysts loading their data.

Multiple Hypotheses Generator.

One of the challenges in conducting an ACH exercise is the generation of a comprehensive list of mutually exclusive hypotheses. This tool allows analysts to work their way systematically and efficiently through this process.

Practice Using ACH! If you want to try out the ACH software, follow these instructions: Download the software following the instructions above. Click on this link to download the practice case study, The Wen Ho Lee Case Study. As you read the case study, ask yourself two questions: What hypotheses would explain Wen Ho Lee's behavior? What information or evidence in the case study would help determine which hypotheses are most likely to be true? Click on this link to download a practice ACH matrix, The Wen Ho Lee ACH matrix. For your convenience, 13 evidence points have been pre-entered; you can still add more points of evidence. You should enter at least three hypotheses across the top of the matrix (under H:1, H:2, H:3). Fill out the matrix by selecting a cell and choosing the appropriate value with the pull down menu. After you have filled out the matrix, go to the top of the sheet and in the box that says Sort Evidence By: click on Diagnosticity. The diagnosticity function will sort your hypotheses from most to least likely and your evidence from most to least discriminating. If you want feedback on how well you did, send us an email message to ach@pherson.org and attach a copy of your completed matrix.