Searching For a Break in GNP
检验美国战后GNP数据是否存在趋势断裂，发现统计证据不足以否定无趋势断裂的原假设，并指出传统显著性水平高估了趋势断裂的可能性，因为断裂日期通常基于数据预检验选择。
It has been suggested that existing estimates of the long-run impact of a surprise move in income may have a substantial upward bias due to the presence of a trend break in post war U.S. GNP data. This paper shows that the statistical evidence does not warrant abandoning the no trend null hypothesis. A key part of the argument is that conventionally computed significance levels overstate the likelihood of the trend break alternative hypothesis. This is because they do not take into account that, in practice, the break date is chosen based on pre-test examination of the data.