SYN-DIGITS: A Synthetic Control Framework for Calibrated Digital Twin Simulation

TL;DR

SYN-DIGITS is a calibration framework that improves the reliability of AI-based digital twin simulations by aligning model predictions with human behavior using synthetic control methods, applicable as a post-processing step.

Contribution

It introduces a model-agnostic, latent space calibration method for digital twins that enhances accuracy and provides error guarantees, based on a formal latent factor model.

Findings

Achieves up to 50% improvement in individual-level correlation.

Reduces distributional discrepancy by 50-90%.

Supports calibration for unseen questions and populations.

Abstract

AI-based persona simulation -- often referred to as digital twin simulation -- is increasingly used for market research, recommender systems, and social sciences. Despite their flexibility, large language models (LLMs) often exhibit systematic bias and miscalibration relative to real human behavior, limiting their reliability. Inspired by synthetic control methods from causal inference, we propose SYN-DIGITS (SYNthetic Control Framework for Calibrated DIGItal Twin Simulation), a principled and lightweight calibration framework that learns latent structure from digital-twin responses and transfers it to align predictions with human ground truth. SYN-DIGITS operates as a post-processing layer on top of any LLM-based simulator and thus is model-agnostic. We develop a latent factor model that formalizes when and why calibration succeeds through latent space alignment conditions, and we systematically evaluate ten calibration methods across thirteen persona constructions, three LLMs, and two datasets. SYN-DIGITS supports both individual-level and distributional simulation for previously unseen questions and unobserved populations, with provable error guarantees. Experiments show that SYN-DIGITS achieves up to 50% relative improvements in individual-level correlation and 50--90% relative reductions in distributional discrepancy compared to uncalibrated baselines.