caddis workshop [causal analysis/diagnosis decision information system] new jersey water...
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CADDIS Workshop [Causal Analysis/Diagnosis Decision Information System]
New Jersey Water Restoration, Protection, and Planning Working Group
Rutgers University, New JerseyMay 7, 2008
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Time Topic Facilitator
10:00 Introduction Host
10:10 Philosophy and Framework of Causal Analysis Cormier
10:50 Analysis and Interpretation of Evidence Schofield
11:30 Identifying the Probable Cause Cormier
12:00 CADDIS Tour— resources for causal analysis Schofield
12:30 Lunch
1:00 CADStat•Enter data•Make a Scatter Plot
Cormier
1:30 Analysis and Interpretation of Evidence•Scatter Plot•Box Plot•Conditional Probability Analysis •Regression and Quantile Regression
Schofield/Cormier
2:30 Screening Assessment Schofield
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Why Stressor Identification?• All states and several
tribes use biological assessments to identify whether streams and small rivers are impaired.
• In many cases, causes of impairment are unknown.
• To set a TMDL (or otherwise address the problem), you must identify a cause.
• It’s defensible & reproducible.
Causes of Impairment
NOTE: Click on the underlined "Causes of Impairment Reported" value to see a listing of those waters with that cause of impairment. Click on the underlined "General Impairment Name" to see the detailed state-reported impairment names.
General Impairment Name Causes of Impairment Reported Percent of Reported
MERCURY 8555 13.45
PATHOGENS 8526 13.41
SEDIMENT 6689 10.52
METALS (OTHER THAN MERCURY)
6389 10.05
NUTRIENTS 5654 8.89
OXYGEN DEPLETION 4568 7.18
PH 3389 5.33
CAUSE UNKNOWN - BIOLOGICAL INTEGRITY
2866 4.51
TEMPERATURE 2854 4.49
HABITAT ALTERATION 2220 3.49
PCBS 2081 3.27
TURBIDITY 2050 3.22
CAUSE UNKNOWN 1356 2.13
PESTICIDES 1322 2.08
SALINITY/TDS/CHLORIDES 996 1.57
FLOW ALTERATION 591 .93
ALGAL GROWTH 510 .80
AMMONIA 415 .65
OTHER TOXIC ORGANICS 339 .53
TOTAL TOXICITY 292 .46
DIOXINS 290 .46
TOXIC INORGANICS 270 .42
FISH CONSUMPTION ADVISORY - POLLUTANT UNSPECIFIED
260 .41
SULFATES 259 .41
NOXIOUS AQUATIC PLANTS
229 .36
OIL AND GREASE 138 .22
OTHER CAUSE 127 .20
TASTE, COLOR AND ODOR
83 .13
CHLORINE 78 .12
FLOATABLES 73 .11
NUISANCE EXOTIC SPECIES
50 .08
NUISANCE NATIVE SPECIES
30 .05
RADIATION 23 .04
CAUSE UNKNOWN - FISH KILLS
19 .03
HARMFUL ALGAL BLOOMS
4 .01
CAUSE UNKNOWN - BIOTOXINS
4 .01
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Success stories
SITE RESULT
Bogue Homo, MS
Identified low DO, high sediment as probable causes of impairment; developed template to expedite TMDLs
Touchet River, WARecommended sediment reduction & restoration of canopy cover
Groundhouse River, MNIdentified data needs & secured funding for data collection
Long Creek, MEDeveloped report examining non-point source TMDLs for urban streams
Naugatuck River, CTUsed applied toxicity tests & modeling to identify toxic effluent as probable cause; TMDL recently approved
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CADDIS is based on a formal method
2005, 2007…2010
http://www.epa.gov/caddisSI Guidance
2002
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General and Specific Causation
• General– Does C cause E?
– Does smoking cause lung cancer?– Does dissolved oxygen reduce mayflies in rivers?
• Case and Cause Specific– Did C cause E?
– Did smoking cause lung cancer in Ronald Fisher?– Did low dissolved oxygen reduce mayflies in my river?
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• Case Specific —Which C caused E?– What exposure and/or genetic predisposition caused
cancer in Ronald Fisher– What stressor(s) are causing reduced mayflies in my river
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Physical Interaction
Causal agents change affected agents by physical interaction.
Directionality The cause precedes its effect
SufficiencyIntensity or frequency of contact with the cause is adequate to produce the observed effect
Sequential Dependence
All effects result from a prior sequence of cause-effect events
Coherence of Characteristics
Specific causal relationships are consistent with scientific theory
Characteristics of Causal Relationships
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Inference of Causal Characteristics
Inference from Definition
Observation The effect is observed to occur with the cause.
Manipulation Changing the cause changes its effect.
PredictionKnowledge from empirical observations or mechanistic studies permits reliable prediction of events.
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Inference from
Observation/ Consistency
Manipulation Prediction
Physical Interaction
Directionality
Sufficiency
Sequential Dependence
Coherence of CharacteristicsC
har
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Inference of Causal Characteristics Provides Evidence of Causal Relationships
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Inference from
Observation/ Consistency
Manipulation Predictability
Physical Interaction
Spatial/Temporal Co-occurrence
Manipulation of co-occurrence; e.g., caging experiment
Evidence of exposure or biological mechanismVerified Prediction
DirectionalityTemporal Sequence
Manipulation of time order
Verified prediction of time order
Sufficiency
Stressor-Response in the Field
Manipulation of duration, concentration, frequency, other factors Laboratory tests of site media
Stressor response from ecological simulation or physiological models
Sequential Dependence
Causal pathway (before and after)
Manipulation of circumstances or pathways leading to the proximate cause
Verified prediction of source, precursor, or subsequent effectAnalogous situations
Coherence of Characteristics
Mechanistically plausibleSymptomology
Verified Prediction of Symptom Analogous stressors
Ch
arac
teri
stic
s o
f p
hys
ical
inte
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ion
sInference of Causal Characteristics Provides
Evidence of Causal Relationships
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Types of Evidence used in CADDIS Characteristic
Spatial/Temporal Co-occurrence with positive reference sites
Physical InteractionSpatial/Temporal Co-occurrence through Time
Spatial/Temporal Co-occurrence Upstream Downstream Comparison
Evidence of Exposure or Biological Mechanism
Temporal Sequence Directionality
Stressor-Response Relationship in the Field
SufficiencyStressor-Response from Laboratory Studies
Stressor-Response from Ecological Simulation Models
Causal Pathway Causal Dependence
SymptomsCoherence
Mechanistically plausible
Laboratory Tests of Site Media (Manipulation)
Verified Predictions
Manipulation of Exposure
Analogous stressors (Prediction)
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General and Specific Causation
•General– Does C cause E?
– Ecological knowledge and theory, regional assessment
• Case and Cause Specific– Did C cause E?
– Good for permits, damage assessment costs, reregistration of chemicals
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• Case Specific —Which C caused E?
– Identifying an unknown cause
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Planning
Analysis
Synthesis
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Planning
Analysis
Synthesis
Decision/Action
Initiator
Common Assessment Process
Define the Case
List Candidate Causes
Evaluate Data from the Case
Evaluate Data from Elsewhere
Identify Probable Cause
Detect or Suspect Biological Impairment
Identify and Apportion Sources
Management Action: Eliminate or Control Sources, Monitor Results
Biological Condition Restored or Protected
Stressor Identification
CADDIS Stressor Identification Process
Problem Resolution
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Our causal strategy (& some notes)
• Identify alternative candidate causes
• Logically eliminate when you can
• Diagnose when you can
• Use strength of evidence for the rest
• Identify most likely cause
– Do not claim proof of causation
– Use a consistent process
– Document evidence & inferences
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Why use a formal method?
• To provide a defensible & reproducible evaluation
• To convince stakeholders
• To increase confidence that remedial or restoration efforts can improve biological condition
• To identify causal relationships that are not immediately apparent
• To prevent biases and other lapses of logic
“Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself – and you are the easiest person to fool.” [Feynman 1964]
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Philosophers of causation
David Hume: Causality as associations between events
Galileo: Causes of effects are knowable
John Stuart Mill:Manipulating cause will change effect
Charles Peirce: Inference to the best explanation
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Philosophers of causation
Ronald Fisher: Controlled experiments with replication and randomization
Karl Pearson: Need to quantify association between variables
Austin Bradford Hill: Causality based on strength of evidence
Robert Koch: Postulates for demonstrating causes of diseases
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• Gives you tools & information to make your causal assessment easier
• You can’t just push a button on CADDIS to determine cause of impairment…
–Will need to use your head–Will need data to generate evidence
What does CADDIS do?