In case of single-factor interest rate models, there is only one state variable, the default-free instantaneous interest rate.

单因子利率模型中，只设定一个状态变量，即无违约风险的瞬时利率。 瞬时利率的运动变化决定了整个利率期限结构的运动变化。

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Unfortunately, the instantaneous interest rate does not exist in real world, so we must use short-term interest rates as its proxy.

但是瞬时利率在现实生活中并不存在，往往要用短期利率进行替代。

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According to the correlation principle and selecting the most frequently traded, largest traded volume item, this article finds that R007 is the best proxy for instantaneous interest rate.

本文按照相关性原则和交易最频繁、成交量最大原则进行了数据选择，找到了瞬时利率的最佳替代利率R007。

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