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Causal Inference for Air Quality Regulations Corwin M. Zigler Accountability for Air Quality Potential Outcomes and Interference Spatial Hierarchical Model Assessing Interference Assumptions Analysis of the 1990 Clean Air Act Amendments [email protected] 1 /21 Estimating Causal Effects of Air Quality Regulations Using Principal Stratification for Spatially-Correlated Multivariate Intermediate Outcomes Corwin M. Zigler Department of Biostatistics, Harvard School of Public Health May 24, 2012
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Page 1: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 1 /21

Estimating Causal Effects of Air QualityRegulations Using Principal Stratification

for Spatially-Correlated MultivariateIntermediate Outcomes

Corwin M. Zigler

Department of Biostatistics, Harvard School of Public Health

May 24, 2012

Page 2: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 2 /21

Air Quality, Health, andRegulation

Accountability Assessment

• Long term exposure to air pollution is bad for health.• EPA estimates ≈ $25 billion per year on air quality

management.• 1970 Clean Air Act.

• For a specific regulatory action:• What were the causal effects on air quality?• What were the causal effects on health?

Page 3: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 3 /21

1990 Clean Air ActAmendments (CAAA)

EPA designates counties as:

1 Attainment of air quality standards for PM10 .2 Nonattainment of air quality standards for PM10 :

• Required states to implement plans to achievestandards.

What were the causal effects of the 1990nonattainment designations for PM10 on:

• Pollution• Ambient concentrations of PM10 and O3 in 1999-2001.

• Health• All-cause Medicare mortality in 2001.

Page 4: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 4 /21

Causal Inference for Air QualityRegulations

1 Potential outcomes in the EPA regulatory environment.

2 Air quality is a posttreatment concomitant variable.• ⇒ Principal stratification.

3 Regulations affect multiple pollutants.• ⇒ Multivariate continuous intermediate variable.

4 Pollution is spatially correlated.• Hierarchical spatial model.

5 Interference between observations (no SUTVA).

Page 5: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 4 /21

Causal Inference for Air QualityRegulations

1 Potential outcomes in the EPA regulatory environment.2 Air quality is a posttreatment concomitant variable.

• ⇒ Principal stratification.

3 Regulations affect multiple pollutants.• ⇒ Multivariate continuous intermediate variable.

4 Pollution is spatially correlated.• Hierarchical spatial model.

5 Interference between observations (no SUTVA).

Page 6: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 4 /21

Causal Inference for Air QualityRegulations

1 Potential outcomes in the EPA regulatory environment.2 Air quality is a posttreatment concomitant variable.

• ⇒ Principal stratification.3 Regulations affect multiple pollutants.

• ⇒ Multivariate continuous intermediate variable.

4 Pollution is spatially correlated.• Hierarchical spatial model.

5 Interference between observations (no SUTVA).

Page 7: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 4 /21

Causal Inference for Air QualityRegulations

1 Potential outcomes in the EPA regulatory environment.2 Air quality is a posttreatment concomitant variable.

• ⇒ Principal stratification.3 Regulations affect multiple pollutants.

• ⇒ Multivariate continuous intermediate variable.4 Pollution is spatially correlated.

• Hierarchical spatial model.

5 Interference between observations (no SUTVA).

Page 8: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 5 /21

Observed Regulation Programand Overall Causal Effect

Observed Regulation Program

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AttainmentNonattainment

No EPA Action

Page 9: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 5 /21

Observed Regulation Programand Overall Causal Effect

Observed Regulation Program

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Observational unit:pollution monitor(point-referenced data)

Overall Causal Effect

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AttainmentNonattainment

No EPA Action

Page 10: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 5 /21

Observed Regulation Programand Overall Causal Effect

Observed Regulation Program

●●

●●●●

●●●●●●●●●●●●●●

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Observational unit:pollution monitor(point-referenced data)

Overall Causal Effect

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AttainmentNonattainment

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AttainmentNonattainment

No EPA Action

Page 11: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 6 /21

Potential Outcomes

Regulation program vector: A = [A(si)]ni=1

• n = 362 locations.• A(si) = 1⇒ i th location nonattainment.• Specific regulation program A = a.

Potential Outcomes• Pollution Xa(s): vector of pollutant concentrations.

• PM10 and O3 .• Mortality Ya(s): all-cause mortality among Medicare

beneficiaries living near a monitor.• ≈ 7 million people aged 65+.

Page 12: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 6 /21

Potential Outcomes

Regulation program vector: A = [A(si)]ni=1

• n = 362 locations.• A(si) = 1⇒ i th location nonattainment.• Specific regulation program A = a.

Potential Outcomes• Pollution Xa(s): vector of pollutant concentrations.

• PM10 and O3 .• Mortality Ya(s): all-cause mortality among Medicare

beneficiaries living near a monitor.• ≈ 7 million people aged 65+.

Page 13: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 7 /21

Spatial Correlation→Interference

• Typical assumption of no interference (SUTVA) likelyviolated.

• Regulations can affect air quality in other areas.

• Full interference: every location interferes with everyother location.

• 2n potential outcomes for each location.• Partial interference.

• Some locations interfere with some other locations.• How to define the interference groups?

Page 14: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 7 /21

Spatial Correlation→Interference

• Typical assumption of no interference (SUTVA) likelyviolated.

• Regulations can affect air quality in other areas.• Full interference: every location interferes with every

other location.• 2n potential outcomes for each location.

• Partial interference.• Some locations interfere with some other locations.• How to define the interference groups?

Page 15: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 7 /21

Spatial Correlation→Interference

• Typical assumption of no interference (SUTVA) likelyviolated.

• Regulations can affect air quality in other areas.• Full interference: every location interferes with every

other location.• 2n potential outcomes for each location.

• Partial interference.• Some locations interfere with some other locations.• How to define the interference groups?

Page 16: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 8 /21

Never Observe PotentialOutcomes Under Regulation

Programs of Interest

Observed Regulation No Regulation Full RegulationA = aobs A = 0 A = 1

i Aobs(si ) Xaobs (si ) Yaobs (si ) X0(si ) Y0(si ) X1(si ) Y1(si )

Observed 1 0 obs obs

obs∗

obs∗ ? ?

Attainment 2 0 obs obs

obs∗ obs∗ ? ?

(black dots)...

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Observed...

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.nonattainment n − 1 1 obs obs

? ? obs∗ obs∗

(red dots) n 1 obs obs

? ? obs∗ obs∗

Page 17: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 8 /21

Never Observe PotentialOutcomes Under Regulation

Programs of Interest

Observed Regulation No Regulation Full RegulationA = aobs A = 0 A = 1

i Aobs(si ) Xaobs (si ) Yaobs (si ) X0(si ) Y0(si ) X1(si ) Y1(si )

Observed 1 0 obs obs obs∗ obs∗ ? ?Attainment 2 0 obs obs obs∗ obs∗ ? ?

(black dots)...

.

.

....

.

.

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.

.

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.

.

.

Observed...

.

.

....

.

.

....

.

.

....

.

.

.nonattainment n − 1 1 obs obs ? ? obs∗ obs∗

(red dots) n 1 obs obs ? ? obs∗ obs∗

Page 18: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 9 /21

Assignment Group InterferenceAssumption (AGIA)

●●

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AttainmentNonattainment

Interference implicitin EPA decisions

⇓Black dots don’tinterfere withRed dots

Page 19: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 10 /21

Estimation

Models• Potential pollution outcomes.

• Multivariate spatial hierarchical model.• Mortality outcomes, conditional on pollution.

• Poisson regression.

• Estimation with data augmentation / MCMC.

Average Causal Effects

• Expected K-Dissociative Effect:• Average effect on mortality in areas where regulation

did not affect pollution.• Expected K-Associative Effect:

• Average effect on mortality in areas where regulationdecreased pollution.

Page 20: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 10 /21

Estimation

Models• Potential pollution outcomes.

• Multivariate spatial hierarchical model.• Mortality outcomes, conditional on pollution.

• Poisson regression.

• Estimation with data augmentation / MCMC.

Average Causal Effects

• Expected K-Dissociative Effect:• Average effect on mortality in areas where regulation

did not affect pollution.

• Expected K-Associative Effect:• Average effect on mortality in areas where regulation

decreased pollution.

Page 21: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 10 /21

Estimation

Models• Potential pollution outcomes.

• Multivariate spatial hierarchical model.• Mortality outcomes, conditional on pollution.

• Poisson regression.

• Estimation with data augmentation / MCMC.

Average Causal Effects

• Expected K-Dissociative Effect:• Average effect on mortality in areas where regulation

did not affect pollution.• Expected K-Associative Effect:

• Average effect on mortality in areas where regulationdecreased pollution.

Page 22: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 11 /21

Spatial Hierarchical Model

X (s) = Z T (s)β + W (s) + ε(s)

• s ≡ specific location.

• X (s) ≡ 4−dimensional vector of pollution concentrations underboth regulations (XA=0(s),XA=1(s)).

• Z (s) ≡ covariates.

• ε(s) ≡ nonspatial (”nugget”) error.

• W (s) ≡ spatially-varying random intercepts.

• W (s) ∼ Multivariate Gaussian Process (MVGP).• Cross-covariance: K (s, s′; ν).

• ν governs spatial decay and smoothness.

Page 23: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 11 /21

Spatial Hierarchical Model

X (s) = Z T (s)β + W (s) + ε(s)

• s ≡ specific location.

• X (s) ≡ 4−dimensional vector of pollution concentrations underboth regulations (XA=0(s),XA=1(s)).

• Z (s) ≡ covariates.

• ε(s) ≡ nonspatial (”nugget”) error.

• W (s) ≡ spatially-varying random intercepts.

• W (s) ∼ Multivariate Gaussian Process (MVGP).• Cross-covariance: K (s, s′; ν).

• ν governs spatial decay and smoothness.

Page 24: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 12 /21

K (s, s′; ν)

Not RegulatedRegulated

sPM

O3

PM

O3

s'PM

O3

PM

O3

K (s, s; ν)

?

K (s′, s′; ν)

?K (s, s; ν) =K (s′, s′; ν)⇒ stationary

K (s, s′; ν) =( · · · ·· · · ·· · · ·· · · ·

)@@@R

��������n

n@@@R

��������

K (s, s′; ν) =( • · · ·· · · ·· · · ·· · · ·

)Corr(PM(s),PM(s′)) = e−ν||s−s′|| (isotropic)

Page 25: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 12 /21

K (s, s′; ν)

Not RegulatedRegulated

sPM

O3

PM

O3

s'PM

O3

PM

O3K (s, s; ν)

?

K (s′, s′; ν)

?K (s, s; ν) =K (s′, s′; ν)⇒ stationary

K (s, s′; ν) =( · · · ·· · · ·· · · ·· · · ·

)@@@R

��������n

n@@@R

��������

K (s, s′; ν) =( • · · ·· · · ·· · · ·· · · ·

)Corr(PM(s),PM(s′)) = e−ν||s−s′|| (isotropic)

Page 26: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 12 /21

K (s, s′; ν)

Not RegulatedRegulated

sPM

O3

PM

O3

s'PM

O3

PM

O3

K (s, s; ν)

?

K (s′, s′; ν)

?K (s, s; ν) =K (s′, s′; ν)⇒ stationary

K (s, s′; ν) =( · · · ·· · · ·· · · ·· · · ·

)@@@R

��������

nn@

@@R

��������

K (s, s′; ν) =( • · · ·· · · ·· · · ·· · · ·

)Corr(PM(s),PM(s′)) = e−ν||s−s′|| (isotropic)

Page 27: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 12 /21

K (s, s′; ν)

Not RegulatedRegulated

sPM

O3

PM

O3

s'PM

O3

PM

O3

K (s, s; ν)

?

K (s′, s′; ν)

?K (s, s; ν) =K (s′, s′; ν)⇒ stationary

K (s, s′; ν) =( · · · ·· · · ·· · · ·· · · ·

)@@@R

��������

nn@

@@R

��������

K (s, s′; ν) =( • · · ·· · · ·· · · ·· · · ·

)

Corr(PM(s),PM(s′)) = e−ν||s−s′|| (isotropic)

Page 28: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 12 /21

K (s, s′; ν)

Not RegulatedRegulated

sPM

O3

PM

O3

s'PM

O3

PM

O3

K (s, s; ν)

?

K (s′, s′; ν)

?K (s, s; ν) =K (s′, s′; ν)⇒ stationary

K (s, s′; ν) =( · · · ·· · · ·· · · ·· · · ·

)@@@R

��������

nn@

@@R

��������

K (s, s′; ν) =( • · · ·· · · ·· · · ·· · · ·

)

Corr(PM(s),PM(s′)) = e−ν||s−s′|| (isotropic)

Page 29: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 13 /21

Specifying Spatial Structure

1 Specify K (s, s; ν)• Covariance matrix for potential pollution concentrations

within a location.• Nonidentifiability⇒ sensitivity parameter.

2 Specify spatial decay for each individual pollutionconcentration.

• Separate isotropic exponential decay functions for eachpollutant.

3 Combine 1. and 2. ⇒ cross-covariance function forMVGP.

• Computational feasibility.• Isoloate nonidentifiable associations between potential

outcomes.

Page 30: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 14 /21

Why a Spatial Model?

Predicting potential outcomes:

• Predict missing potential outcomes at s usinginformation at surrounding locations.

• Use estimates of ν to assess interference assumption.

Not RegulatedRegulated

●●

●●

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● ●●

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●●

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●●

●●●●●●

●●

●●●

●●●●

●●●

s

����

ν &%'$

ν

Page 31: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 14 /21

Why a Spatial Model?

Predicting potential outcomes:

• Predict missing potential outcomes at s usinginformation at surrounding locations.

• Use estimates of ν to assess interference assumption.

Not RegulatedRegulated

●●

●●

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● ●●

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●●●

s

����

ν

&%'$

ν

Page 32: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 14 /21

Why a Spatial Model?

Predicting potential outcomes:

• Predict missing potential outcomes at s usinginformation at surrounding locations.

• Use estimates of ν to assess interference assumption.

Not RegulatedRegulated

●●

●●

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● ●●

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s

iν ����

ν

&%'$

ν

Page 33: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 15 /21

Assess Interference Assumption

ν̂ has implications of interference

• ν̂ ⇒ estimated correlation between measurements attwo locations.

• Examine correlations between observations assumednot to interfere.

• Substantial correlation⇒ violation of AGIA.

Page 34: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 16 /21

Assessment of AGIA for PM10

Figure: PM10 , ν̂ = 3.13

Correlation at distance ds

Freq

uenc

y

0.0 0.1 0.2 0.3 0.4 0.5 0.6

020

4060

8010

0

Correlation > 0.2530 locations

Page 35: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 17 /21

Assessment of AGIA for O3

Figure: O3 , ν̂ = 2.68

Correlation at distance ds

Freq

uenc

y

0.0 0.1 0.2 0.3 0.4 0.5 0.6

010

2030

4050

60

Correlation > 0.2554 locations

Page 36: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 18 /21

Associative and DissociativeEffects for PM10

●●

●●

●●●

●●●

●●●●

●●

●●●

●●●

●●

●●

Dea

ths/

1000

EDE EAE

−8−6

−4−2

02

4

ω=0 ω=0.3 ω=0.6 ω=0.9 ω=0 ω=0.3 ω=0.6 ω=0.9

Causal effect on heath in areas where:regulation does not

affect PM10regulation causally

reduces PM10

Page 37: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 19 /21

Associative and DissociativeEffects for joint effect on both

PM10 and O3

●●●

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● ●●

●●●

Dea

ths/

1000

EDE EAE−1

0−8

−6−4

−20

24

68

ω=0 ω=0.3 ω=0.6 ω=0.9 ω=0 ω=0.3 ω=0.6 ω=0.9

Causal effect on heath in areas where:regulation does not

affect PM10 or O3regulation causally

reduces PM10 and O3

Page 38: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 20 /21

Summary

Causal inference for accountability assessment

• Complex regulatory environment.• Causal inference with spatial data.• Principal stratification

• Multivariate intermediate variable.• Multipollutant approach.

• Assumptions about interference between observations.• What do we assume?• How do we assess?• What are the implications of violations?

Page 39: Estimating Causal Effects of Air Quality Regulations Using ...estuart/CZACICSlides.pdf · Estimating Causal Effects of Air Quality Regulations Using Principal Stratification ...

CausalInference forAir Quality

Regulations

Corwin M.Zigler

Accountabilityfor Air Quality

PotentialOutcomesandInterference

SpatialHierarchicalModel

AssessingInterferenceAssumptions

Analysis ofthe 1990Clean Air ActAmendments

[email protected] 21 /21

Thank You

Acknowledgments

• Francesca Dominici• Yun Wang• Funding: Health Effects Institute.• Publication: Zigler CM, Dominici F, and Wang Y.

Estimating causal effects of air quality regulations usingprincipal stratification for spatially-correlatedmultivariate intermediate outcomes. Biostatistics 2012;13(2): 289–302.


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