Attempts to measure economic aggregates precisely have failed to forecast the boom and bust cycle accurately, but economists who focused on basic cause-and-effect relationships among economic phenomena were among the most prescient predictors of the 2000 stock-market bubble and crash. While some analysts noted correctly that price-to-earnings ratios were unduly inflated, it was economists of the Austrian school who offered an explanation for why stock-market valuations had become inflated and unsustainable.