Christopher A. Sims explores the implications of rational inattention, where individuals have limited information-processing capacity. He shows that this constraint can mimic the role of signal extraction or adjustment costs in standard economic models. The theory resembles dynamic rational expectations models but offers different policy implications. Sims argues that limited information-processing capacity explains macroeconomic behavior, including price stickiness and delayed responses to shocks. He uses information theory to model how agents process data through finite-capacity channels, leading to predictions about how agents respond to economic signals. The theory suggests that agents' responses to macroeconomic data are influenced by their information-processing constraints, which can result in smoothed or delayed reactions. Sims also discusses how this framework can be applied to economic models, such as the permanent income model, to analyze how agents respond to income shocks. The results show that information-processing constraints can lead to delayed responses and smoothed behavior, which aligns with observed macroeconomic patterns. Sims concludes that the theory provides a useful framework for understanding economic behavior and policy implications, particularly in the context of macroeconomic time series.Christopher A. Sims explores the implications of rational inattention, where individuals have limited information-processing capacity. He shows that this constraint can mimic the role of signal extraction or adjustment costs in standard economic models. The theory resembles dynamic rational expectations models but offers different policy implications. Sims argues that limited information-processing capacity explains macroeconomic behavior, including price stickiness and delayed responses to shocks. He uses information theory to model how agents process data through finite-capacity channels, leading to predictions about how agents respond to economic signals. The theory suggests that agents' responses to macroeconomic data are influenced by their information-processing constraints, which can result in smoothed or delayed reactions. Sims also discusses how this framework can be applied to economic models, such as the permanent income model, to analyze how agents respond to income shocks. The results show that information-processing constraints can lead to delayed responses and smoothed behavior, which aligns with observed macroeconomic patterns. Sims concludes that the theory provides a useful framework for understanding economic behavior and policy implications, particularly in the context of macroeconomic time series.