The main conclusions are: (1)The return rate of stock index is verified further that it's not normal but with heavy tail;

主要的结论是：进一步验证了股指收益率的分布不是正态的，而是具有厚尾性；

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The single-factor model thinks, the rate of return of the stock can be explained with system risk and none system risk together, but it limits the system risk in a factor (such as market index).

单因素模型认为，股票的收益率可以由系统风险和非系统风险联合解释，但它把系统风险限制在一个因素（如市场指数）当中。

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According to statistical analysis on Shanghai stock index, the distribution of the rate of return is non-positive skewed, and there exists an autoregressive heteroskedasticity in the rate of return.

通过对上证指数的统计分析表明，上证指数的收益率分布表现出非正态性，并存在自回归条件异方差的特征。

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