进一步研究表明，波动性和相关性的多尺度变化导致了最小方差对冲比率及对冲效率呈相似规律的多尺度变化。

The empirical results suggested that the correlation and volatility ratio between index futures and spot vary over various time scales.

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然而，没有哪种模式或对冲避险策略是通过此事，认为这是完全套期保值比率会随时间而改变。

However, no matter which kind of hedge model or hedge strategy is adopted, it is totally considered that hedge ratio will vary with time.

youdao

然而，没有哪种模式或对冲避险策略是通过此事，认为这是完全套期保值比率会随时间而改变。

However, no matter which kind of hedge model or hedge strategy is adopted, it is totally considered that hedge ratio will vary with time.

youdao