Suppose that you could follow quantitative rules that allowed you to weed out the bad apples, say, the countries likely to perform badly and thus have low stock returns over time. If you weed out most of the bad and the ugly, you end up picking more of the good apples – and do better than average.
但第三种投资方法，即所谓的“聪明”（或“强化”）贝塔，最近日渐流行起来。假设你可以遵循能够让你剔除坏标的（比如表现拙劣、因此长期股票回报较低的国家）的量化规则。如果你剔除了大部分坏标的和丑标的，你就能握有更多好标的——从而获得比平均水平更好的表现。