Robert E. Lucas, Jr. critiques the econometric tradition in economic policy evaluation, arguing that it is fundamentally flawed. He highlights the conflict between the theoretical tradition and econometric forecasting models, which have implied long-run unemployment-inflation trade-offs. Lucas contends that econometric models are designed for short-term forecasting and cannot reliably simulate the consequences of alternative policies. He emphasizes that the "natural rate hypothesis" and the "theory of economic policy" are based on assumptions that do not hold in reality, as agents adapt to changing conditions. Lucas argues that econometric models fail to account for parameter drift, leading to unreliable long-term policy simulations. He also critiques the use of adaptive forecasting methods, which adjust to recent data but do not reflect the true structure of the economy. Lucas concludes that the econometric tradition is in need of major revision, as it cannot provide meaningful insights into long-term policy outcomes. He provides examples from consumption, investment, and Phillips curves to illustrate the limitations of econometric models in capturing the complexities of economic behavior. Ultimately, Lucas argues that the econometric tradition is insufficient for evaluating economic policy and that a more realistic approach is needed.Robert E. Lucas, Jr. critiques the econometric tradition in economic policy evaluation, arguing that it is fundamentally flawed. He highlights the conflict between the theoretical tradition and econometric forecasting models, which have implied long-run unemployment-inflation trade-offs. Lucas contends that econometric models are designed for short-term forecasting and cannot reliably simulate the consequences of alternative policies. He emphasizes that the "natural rate hypothesis" and the "theory of economic policy" are based on assumptions that do not hold in reality, as agents adapt to changing conditions. Lucas argues that econometric models fail to account for parameter drift, leading to unreliable long-term policy simulations. He also critiques the use of adaptive forecasting methods, which adjust to recent data but do not reflect the true structure of the economy. Lucas concludes that the econometric tradition is in need of major revision, as it cannot provide meaningful insights into long-term policy outcomes. He provides examples from consumption, investment, and Phillips curves to illustrate the limitations of econometric models in capturing the complexities of economic behavior. Ultimately, Lucas argues that the econometric tradition is insufficient for evaluating economic policy and that a more realistic approach is needed.