HKUST · IEDA · Interpretable Evaluation Lab

IE Lab — understanding decisions
to improve them

Department of Industrial Engineering and Decision Analytics

We develop rigorous frameworks to evaluate and explain decisions made by algorithms, AI systems, and human policies — grounded in causal inference, mechanistic interpretability, and stochastic optimization. Our work is driven by real-world problems in online platforms, experimentation, and AI deployment.

Causal InferenceIdentifying causal effects from both observational data and randomized experiments — with methods that handle confounding, interference, and distribution shift across platforms and policy settings. Mechanistic InterpretabilityCircuit-level analysis, sparse autoencoders, and structural causal models to understand how AI systems internally represent knowledge and arrive at decisions. Policy EvaluationAssessing how well a decision policy performs — from offline data, observational records, or simulation — to inform better policy design in healthcare, operations, and AI systems. Experimental DesignPrincipled experimental frameworks for online platforms — addressing interference, anomalous data, and valid statistical inference under complex market dynamics. Reinforcement LearningLearning optimal sequential decision strategies from interaction and feedback — with foundations in reward design, exploration, and generalization across dynamic environments. Online PlatformsModeling two-sided markets, recommendation systems, and large-scale experimentation infrastructure to inform platform-level policy and resource allocation. Distributional RobustnessOptimization methods that remain reliable under distribution shift — addressing model misspecification, covariate shift, and out-of-distribution generalization. SimulationStochastic simulation, physics-based simulation, agent-based simulation, and LLM-driven simulation — to evaluate policies and understand complex system behavior.
Nian Si
Nian Si
司念
Assistant Professor
HKUST IEDA
PhD · Stanford · 2023
About
What We Do

The IE Lab (Interpretable Evaluation Lab) is a research group in the Department of Industrial Engineering and Decision Analytics at the Hong Kong University of Science and Technology, led by Prof. Nian Si.

Our research sits at the intersection of operations research, statistics, and machine learning. We ask: how can we evaluate whether a decision — made by a person, an algorithm, or an AI agent — is truly good? And how can we understand why it works or fails?

We work closely with industry partners to ground our methods in the operational realities of large-scale platforms, including online experimentation systems, recommendation engines, and AI-assisted decision pipelines.

Pillar 01
Mechanistic Interpretability
Circuit-level analysis, sparse autoencoders, and structural causal model to understand how AI models represent knowledge and make decisions.
Pillar 02
Causal Inference & Experimental Design
Reliable causal estimation in complex settings — interference, two-sided platforms, and heavy-tail data.
Pillar 03
Policy Evaluation & Reinforcement Learning
Robust Markov decision processes, average-reward criteria, and simulation-based methods for stochastic and adversarial environments.
Pillar 04
Simulation
Platform simulation, large-scale system simulation, and LLM-based simulation for decision evaluation and policy testing.
Research
Featured Projects
People
Our Team
Nian Si
Nian Si
Principal Investigator
Assistant Professor
Zijun Chen
Zijun Chen
PhD Student
2022 Fall –
co-advised w/ Ke Yi (CSE)
Weitao Cheng
Weitao Cheng
PhD Student
2025 Fall –
Zhenghao Li
Zhenghao Li
PhD Student
2026 Spring –
Ning Xu
Ning Xu
PhD Student
2026 Spring –
Shihan Tang
Shihan Tang
PhD Student
2026 Fall –
Kejie Zhao
Kejie Zhao
PhD Student
2026 Fall –
Collaborations
Industry Partners
WeChat (腾讯)
WeBank (微众银行)