AWS Responsible AI Seminar
"The biggest lesson that can be read from 70 years of AI research is that general methods that leverage computation are ultimately the most effective, and by a large margin. [...] Seeking an improvement that makes a difference in the shorter term, researchers seek to leverage their human knowledge of the domain, but the only thing that matters in the long run is the leveraging of computation. [...]
We want AI agents that can discover like we can, not which contain what we have discovered."
The Bitter Lesson, Rich Sutton 2019
What parts of the image are important for this prediction?
What are the subsets of the input so that
Post-hoc Interpretability Methods
Interpretable by
construction
Post-hoc Interpretability Methods
Interpretable by
construction
efficiency
nullity
symmetry
exponential complexity
Lloyd S Shapley. A value for n-person games. Contributions to the Theory of Games, 2(28):307–317, 1953.
Let be an -person cooperative game with characteristic function
How important is each player for the outcome of the game?
inputs
responses
predictor
inputs
responses
predictor
inputs
responses
predictor
Scott Lundberg and Su-In Lee. A Unified Approach to Interpreting Model Predictions, NeurIPS , 2017
inputs
responses
predictor
Question 1)
Can we resolve the computational bottleneck (and when)?
Question 2)
What do these coefficients mean, statistically?
Question 3)
How to go beyond input-features explanations?
Time permitting... an observation on fairness
We focus on data with certain structure:
Example:
if contains a sick cell
Question 1) Can we resolve the computational bottleneck (and when) ?
We focus on data with certain structure:
h-Shap runs in linear time
Under A1, h-Shap \(\to\) Shapley
Fast hierarchical games for image explanations, Teneggi, Luster & S., IEEE Transactions on Pattern Analysis and Machine Intelligence, 2022
Local models
Observation: Restrict computation of \(\phi_i(f)\) to local areas of influence given by a graph structure
L-Shap
C-Shap
\(\Rightarrow\) complexity \(\mathcal O(2^k n)\)
[Chen et al, 2019]
Local models
[Chen et al, 2019]
Observation: Restrict computation of \(\phi_i(f)\) to local areas of influence given by a graph structure
\(\Rightarrow\) complexity \(\mathcal O(2^k n)\)
Correct approximations (informal statement)
Let \(S\subset \mathcal N_k(i)\). If \((X_i \perp\!\!\!\perp X_{[n]\setminus S} | X_T) \) and \((X_i \perp\!\!\!\perp X_{[n]\setminus S} | X_T,Y) \) for any \(T\subset S\setminus i\).
Then \(\hat{\phi}^k_i(v) = \phi_i(v)\)
(and approximately bounded otherwise, controlled)
Question 2) What do these coefficients mean, statistically?
[Candes et al, 2018]
Question 2) What do these coefficients mean, statistically?
XRT: eXplanation Randomization Test
returns a \(\hat{p}_{i,S}\) for the test above
Given the Shapley coefficient of any feature
Then
and the (expected) p-value obtained for , i.e. ,
Theorem:
Teneggi, Bharti, Romano, and S. "SHAP-XRT: The Shapley Value Meets Conditional Independence Testing." TMLR (2023).
Question 3)
How to go beyond input-features explanations?
Is the piano important for \(\hat Y = \text{cat}\)?
How can we explain black-box predictors with semantic features?
Is the piano important for \(\hat Y = \text{cat}\), given that there is a cute mammal in the image?
Is the presence of \(\color{Blue}\texttt{edema}\) important for \(\hat Y = \text{lung opacity}\)?
How can we explain black-box predictors with semantic features?
Is the presence of \(\color{magenta}\texttt{devices}\) important for \(\hat Y = \texttt{lung opacity}\), given that there is \(\color{blue}\texttt{edema}\) in the image?
lung opacity
cardiomegaly
fracture
no findding
Concept Bank: \(C = [c_1, c_2, \dots, c_m] \in \mathbb R^{d\times m}\)
Embeddings: \(H = f(X) \in \mathbb R^d\)
Semantics: \(Z = C^\top H \in \mathbb R^m\)
Concept Bank: \(C = [c_1, c_2, \dots, c_m] \in \mathbb R^{d\times m}\)
Concept Activation Vectors
(Kim et al, 2018)
\(c_\text{cute}\)
Vision-language models
(CLIP, BLIP, etc... )
Concept Bank: \(C = [c_1, c_2, \dots, c_m] \in \mathbb R^{d\times m}\)
Vision-language models
(training)
[Radford et al, 2021]
[Bhalla et al, "Splice", 2024]
[Koh et al '20, Yang et al '23, Yuan et al '22 ]
\(\tilde{Y} = \hat w^\top Z\)
\(\hat w_j\) is the importance of the \(j^{th}\) concept
Desiderata
\(C = \{\text{``cute''}, \text{``whiskers''}, \dots \}\)
Global Importance
\(H^G_{0,j} : \hat{Y} \perp\!\!\!\perp Z_j \)
Global Conditional Importance
\(H^{GC}_{0,j} : \hat{Y} \perp\!\!\!\perp Z_j | Z_{-j}\)
Global Importance
\(C = \{\text{``cute''}, \text{``whiskers''}, \dots \}\)
\(H^G_{0,j} : g(f(X)) \perp\!\!\!\perp c_j^\top f(X) \)
Global Conditional Importance
\(H^{GC}_{0,j} : g(f(X)) \perp\!\!\!\perp c_j^\top f(X) | C_{-j}^\top f(X)\)
\(H^G_{0,j} : \hat{Y} \perp\!\!\!\perp Z_j \)
\(H^{GC}_{0,j} : \hat{Y} \perp\!\!\!\perp Z_j | Z_{-j}\)
"The classifier (its distribution) does not change if we condition
on concepts \(S\) vs on concepts \(S\cup\{j\} \)"
\(C = \{\text{``cute''}, \text{``whiskers''}, \dots \}\)
Local Conditional Importance
\[H^{j,S}_0:~ g({\tilde H_{S \cup \{j\}}}) \overset{d}{=} g(\tilde H_S), \qquad \tilde H_S \sim P_{H|Z_S = C_S^\top f(x)} \]
"The classifier (its distribution) does not change if we condition
on concepts \(S\) vs on concepts \(S\cup\{j\} \)"
\(\hat{Y}_\text{gas pump}\)
\(Z_S\cup Z_{j}\)
\(Z_{S}\)
\(Z_j=\)
Local Conditional Importance
\[H^{j,S}_0:~ g({\tilde H_{S \cup \{j\}}}) \overset{d}{=} g(\tilde H_S), \qquad \tilde H_S \sim P_{H|Z_S = C_S^\top f(x)} \]
"The classifier (its distribution) does not change if we condition
on concepts \(S\) vs on concepts \(S\cup\{j\} \)"
\(\hat{Y}_\text{gas pump}\)
\(\hat{Y}_\text{gas pump}\)
\(Z_S\cup Z_{j}\)
\(Z_{S}\)
\(Z_S\cup Z_{j}\)
\(Z_{S}\)
Local Conditional Importance
\(Z_j=\)
\(Z_j=\)
\[H^{j,S}_0:~ g({\tilde H_{S \cup \{j\}}}) \overset{d}{=} g(\tilde H_S), \qquad \tilde H_S \sim P_{H|Z_S = C_S^\top f(x)} \]
we can sample from these
\(H^G_{0,j} : \hat{Y} \perp\!\!\!\perp Z_j \iff P_{\hat{Y},Z_j} = P_{\hat{Y}} \times P_{Z_j}\)
Testing importance via two-sample tests
\(H^{GC}_{0,j} : \hat{Y} \perp\!\!\!\perp Z_j | Z_{-j} \iff P_{\hat{Y}Z_jZ_{-j}} = P_{\hat{Y}\tilde{Z}_j{Z_{-j}}}\)
\(\tilde{Z_j} \sim P_{Z_j|Z_{-j}}\)
[Shaer et al, 2023]
[Teneggi et al, 2023]
\[H^{j,S}_0:~ g({\tilde H_{S \cup \{j\}}}) \overset{d}{=} g(\tilde H_S), \qquad \tilde H_S \sim P_{H|Z_S = C_S^\top f(x)} \]
Goal: Test a null hypothesis \(H_0\) at significance level \(\alpha\)
Standard testing by p-values
Collect data, then test, and reject if \(p \leq \alpha\)
Online testing by e-values
Any-time valid inference, monitor online and reject when \(e\geq 1/\alpha\)
[Shaer et al. 2023, Shekhar and Ramdas 2023, Podkopaev et al 2023]
Online testing by e-values
Any-time valid inference, track and reject when \(e\geq 1/\alpha\)
Fair game (test martingale): \(~~\mathbb E_{H_0}[\kappa_t | \text{Everything seen}_{t-1}] = 0\)
\(v_t \in (0,1):\) betting fraction
\(\kappa_t \in [-1,1]\) payoff
[Grünwald 2019, Shafer 2021, Shaer et al. 2023, Shekhar and Ramdas 2023. Podkopaev et al., 2023]
\(\mathbb P_{H_0}[\exists t \in \mathbb N: K_t \leq 1/\alpha]\leq \alpha\)
Goal: Test a null hypothesis \(H_0\) at significance level \(\alpha\)
Online testing by e-values
Any-time valid inference, track and reject when \(e\geq 1/\alpha\)
Fair game (test martingale): \(~~\mathbb E_{H_0}[\kappa_t | \text{Everything seen}_{t-1}] = 0\)
\(v_t \in (0,1):\) betting fraction
\(\kappa_t \in [-1,1]\) payoff
[Grünwald 2019, Shafer 2021, Shaer et al. 2023, Shekhar and Ramdas 2023. Podkopaev et al., 2023]
\(\mathbb P_{H_0}[\exists t \in \mathbb N: K_t \leq 1/\alpha]\leq \alpha\)
Goal: Test a null hypothesis \(H_0\) at significance level \(\alpha\)
Data efficient
Rank induced by rejection time
Online testing by e-values
\(v_t \in (0,1):\) betting fraction
\(H_0: ~ P = Q\)
\(\kappa_t = \text{tahn}({\color{teal}\rho(X_t)} - {\color{teal}\rho(Y_t)})\)
Payoff function
\({\color{black}\text{MMD}(P,Q)} : \text{ Maximum Mean Discrepancy}\)
\({\color{teal}\rho} = \underset{\rho\in \mathcal R:\|\rho\|_\mathcal R\leq 1}{\arg\sup} ~\mathbb E_P [\rho(X)] - \mathbb E_Q[\rho(Y)]\)
\( K_t = K_{t-1}(1+\kappa_t v_t)\)
Data efficient
Rank induced by rejection time
[Shaer et al. 2023, Shekhar and Ramdas 2023, Podkopaev et al 2023]
rejection time
rejection rate
Important Semantic Concepts
(Reject \(H_0\))
Unimportant Semantic Concepts
(fail to reject \(H_0\))
Type 1 error control
False discovery rate control
Important Semantic Concepts
(Reject \(H_0\))
Unimportant Semantic Concepts
(Fail to reject)
rejection time
rejection rate
0.0
1.0
What concepts does BiomedVLP find important to predict ?
lung opacity
Hemorrhage
No Hemorrhage
Hemorrhage
Hemorrhage
intraparenchymal
subdural
subarachnoid
intraventricular
epidural
intraparenchymal
subarachnoid
intraventricular
epidural
subdural
intraparenchymal
subarachnoid
subdural
epidural
intraventricular
intraparenchymal
subarachnoid
intraventricular
epidural
subdural
(+)
(-)
(-)
(-)
(-)
(+)
(-)
(+)
(-)
(-)
(+)
(+)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
Global Importance
Global Conditional Importance
Semantic comparison of vision-language models
Question 1)
Can we resolve the computational bottleneck (and when)?
Question 2)
What do these coefficients mean statistically?
Question 3)
How to go beyond input-features explanations?
Distributional assumptions + hierarchical extensions
Allow us to conclude on differences in distributions
Use online testing by betting for semantic concepts
Inputs (features): \(X\in\mathcal X \subset \mathbb R^d\)
Responses (labels): \(Y\in\mathcal Y = \{0,1\}\)
Sensitive attributes \(Z \in \mathcal Z \subseteq \mathbb R^k \) (sex, race, age, etc)
\((X,Y,Z) \sim \mathcal D\)
Eg: \(Z_1: \) biological sex, \(X_1: \) BMI, then
\( g(Z,X) = \boldsymbol{1}\{Z_1 = 1 \land X_1 > 35 \}: \) women with BMI > 35
Goal: ensure that \(f\) is fair w.r.t groups \(g \in \mathcal G\)
Group memberships \( \mathcal G = \{ g:\mathcal X \times \mathcal Z \to \{0,1\} \} \)
Predictor \( f(X) : \mathcal X \to [0,1]\) (e.g. likelihood of X having disease Y)
Observation 1:
measuring (& correcting) for MA/MC requires samples over \((X,Y,Z)\)
Definition: \(\text{MA} (f,g) = \big| \mathbb E [ g(X,Z) (f(X) - Y) ] \big| \)
\(f\) is \((\mathcal G,\alpha)\)-multiaccurate if \( \max_{g\in\mathcal G} \text{MA}(f,g) \leq \alpha \)
Definition: \(\text{MC} (f,g) = \mathbb E\left[ \big| \mathbb E [ g(X,Z) (f(X) - Y) | f(X) = v] \big| \right] \)
\(f\) is \((\mathcal G,\alpha)\)-multicalibrated if \( \max_{g\in\mathcal G} \text{MC}(f,g) \leq \alpha \)
Observation 2: That's not always possible...
Observation 2: That's not always possible...
We observe samples over \((X,Y)\) to obtain \(\hat Y = f(X)\) for \(Y\)
\( \text{MSE}(f) = \mathbb E [(Y-f(X))^2 ] \)
A developer provides us with proxies \( \color{Red} \hat{g} : \mathcal X \to \{0,1\} \)
\( \text{err}(\hat g) = \mathbb P [({\color{Red}\hat g(X)} \neq {\color{blue}g(X,Z)} ] \)
[Awasti et al, '21][Kallus et al, '22][Zhu et al, '23][Bharti et al, '24]
Question
Can we (how) use \(\hat g\) to measure (and correct) \( (\mathcal G,\alpha)\)-MA/MC?
Theorem [Bharti, Clemens-Sewall, Yi, S.]
With access to \((X,Y)\sim \mathcal D_{\mathcal{XY}}\), proxies \( \hat{\mathcal G}\) and predictor \(f\)
\[ \max_{\color{Blue}g\in\mathcal G} MC(f,{\color{blue}g}) \leq \max_{\color{red}\hat g\in \hat{\mathcal{G}} } B(f,{\color{red}\hat g}) + MC(f,{\color{red}\hat g}) \]
with \(B(f,\hat g) = \min \left( \text{err}(\hat g), \sqrt{MSE(f)\cdot \text{err}(\hat g)} \right) \)
true error
worst-case error
CheXpert: Predicting abnormal findings in chest X-rays
(not accessing race or biological sex)
\(f(X): \) likelihood of \(X\) having \(\texttt{pleural effusion}\)
Take-home message
Jacopo Teneggi
JHU
Beepul Bharti
JHU
Teneggi et al, SHAP-XRT: The Shapley Value Meets Conditional Independence Testing, TMLR (2023).
Teneggi et al, Fast hierarchical games for image explanations, Teneggi, Luster & S., IEEE TPAMI (2022)
Teneggi & S., Testing Semantic Importance via Betting, Neurips (2024).
Yaniv Romano Technion
Bharti et al, Multiaccuracy and Multicalibration via Proxy Groups, ICML (2025).