hypothesis mapping as an alternative to ach · 2019-01-15 · loretta’s hyundai excel was...
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Hypothesis Mapping as an Alternative to ACH
Dr. Tim van Gelder University of Melbourne
Principal, Austhink Consulting [email protected]
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Analysis of Competing Hypotheses
“Classic” ACH Method
1. Start with a table or matrix. 2. Enter all relevant hypotheses
across the top of the table. 3. Enter all items of evidence down
the left side of the table. 4. For each item of evidence,
indicate its bearing (+,-, ?) on every hypothesis.
5. Refine the table, revising the hypotheses and setting aside “useless” (non-diagnostic) evidence.
6. Seek additional evidence, looking to disprove hypotheses.
7. Make assessment, focusing on negative evidence.
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Some strengths of ACH
• It is a structured analytic method (?)
• It is designed to counteract cognitive limitations - particularly confirmation bias (but does it really?)
• It uses a simple, familiar external representation (matrix)
• The matrix structure accommodates the many-many relationship between evidence and hypotheses
• It helps create a common/shared understanding of a problem
• It creates an “audit trail” of thinking
Some things I don’t know…
• To what extent is ACH actually used on the job in intelligence analysis?
• To what extent does ACH in fact improve/hamper on-the-job performance?
• To what extent has classic ACH been superseded by any better methodology?
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So I will:
• Focus on “classic” ACH
• Focus particularly on the use of a matrix
• Focus on problems inherent to use of a matrix structure
Whatever happened to Loretta Cohen? You’re a police investigator. You have inherited a Missing Persons case from someone else. This is the information gathered so far. Loretta Cohen works (or worked) as the PA to the Finance Manager at Patrick Stevedores. She was reported missing on Wednesday 3 May, after failing to turn up to work on Monday 1 May. Her colleagues pointed out that three lots of $50,000 have gone missing from the Finance Department over the last six months. Loretta’s Hyundai Excel was discovered parked near the cliffs at the surf beach. Loretta is an orphan and an only child. Friends at work say Loretta broke up with her boyfriend 6 weeks ago. They also reported that Loretta seemed to be upset by almost daily phone calls from him until about a week before her disappearance. Subsequent investigation has revealed that Loretta’s former boyfriend, 34 year old Mark Tyson, has a conviction for aggravated assault from ten years ago. When the previous investigator had a look at Loretta’s flat, nothing was obviously missing; but it appears Loretta was in letter correspondence with an Islamic activist claiming to be planning a suicide attack in Tel Aviv, and her personal diary described a recent sense of hopelessness. According to neighbors, a mysterious white van has been seen parked outside Loretta’s apartment block for long periods of time, with a man sitting inside it.
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H1 H2 H3 H4 H5 H6 H7
Killed by
work
colleague Suicide
Killed by
boyfriend
Ran away
to join
terrorists
Killed by
burglar
E1 Worked as PA to Finance
Manager + + ? ? ? E2 3 x 50K gone missing from
Finance Dept + + ? + ? E3 Loretta’s car parked near
cliffs at surf beach ? + ? ? - E4 An orphan and only child
? + ? + ? E5 Broke up with boyfriend 6
weeks ago ? + + + ? E6 Upset by daily phone calls
from boyfriend ? + + + ? E7 Boyfriend conviction for
assault ? ? + ? ? E8 Nothing missing from flat
? + + ? - E9 Correspondence with Islamic
activist planning suicide
attack ? + ? + ?
E10 Mysterious white van outside
apartment + ? + ? +
Problems with ACH
• Requires far too many discrete judgments
– Where many of those are pointless
• Oversimplifies evidence-hypothesis relationship
• Treats hypothesis sets as flat
• Treats evidence set as flat
• Discombobulating
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Requires too many discrete judgments
“The exercise we do is a two-day counter terror problem with 130 pieces of evidence. If students assess all evidence in order to attenuate selection bias, and they test 4 hypotheses, they are making 520 individual judgments. Ouch.”
H1 H2 H3 H4 H5 H6 H7
Killed by
work
colleague Suicide
Killed by
boyfriend
Ran away
to join
terrorists
Killed by
burglar
E1 Worked as PA to Finance
Manager + + ? ? ? E2 3 x 50K gone missing from
Finance Dept + + ? + ? E3 Loretta’s car parked near
cliffs at surf beach ? + ? ? - E4 An orphan and only child
? + ? + ? E5 Broke up with boyfriend 6
weeks ago ? + + + ? E6 Upset by daily phone calls
from boyfriend ? + + + ? E7 Boyfriend conviction for
assault ? ? + ? ? E8 Nothing missing from flat
? + + ? - E9 Correspondence with Islamic
activist planning suicide
attack ? + ? + ?
E10 Mysterious white van outside
apartment + ? + ? +
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Oversimplifies Evidence-Hypothesis Relationship
• Matrix structure can’t represent co-premise structures (assumptions, auxiliary hypotheses)
H1 H2 H3 H4 H5 H6 H7
Kill
ed b
y w
ork
colle
agu
e
Suic
ide
Kill
ed b
y b
oyf
rien
d
Ra
n a
way
to
join
terr
ori
sts
Kill
ed b
y b
urg
lar
E8 Nothing missing from
flat
? + + ? -
Treats hypothesis sets as flat
• Hypotheses are just listed across the top
• This neglects meaningful structure in the hypothesis set and creates unnecessary work
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Treats evidence set as flat
• Evidence items listed down the side
• No way to display sub-ordinate arguments & evidence
It’s discombobulating…
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Or more generally, ACH…
• Fundamentally Flawed Logically
– misconceives hypothesis sets, evidence sets, and the relationships between them
• Fundamentally Flawed Psychologically
– Decontextualising and Discombobulating
– Misconceives the nature of analytical expertise
Hypothesis Mapping
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Simple Hypothesis Mapping Method
1. Identify Issue(s). Write in a question box.
2. Develop Hypotheses. Add Hypothesis boxes to map.
3. Marshal Evidence. Add Evidence and Counter-Evidence boxes to map.
4. Evaluate Hypotheses. Identify favoured hypotheses.
5. Test Hypotheses. Seek new evidence challenging favoured hypotheses. Add to map.
6. Draw Conclusions. Rate plausibility of hypotheses.
Loretta Hypothesis Map (Simple)
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Loretta Hypothesis Map
Structured Hypothesis Set
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…allows evidence to be correctly located
And makes it visually transparent how much you’ve got and where gaps are
Structured Evidence Sets
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Co-premise/auxiliary hypotheses
Co-premise/auxiliary hypotheses
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HM Strengths
• Remedies many major problems of ACH
• Intuitive visual format
• Compatible with other methodologies
– Argument Mapping
– Decision Mapping
– Pyramid Principle
• Logic trail
Hypothesis Mapping Weaknesses
• Uses lots of space
• Evidence may need to be duplicated
• More dependent on custom software tools