With the fantastic spurt of science and modern technology throughout the world, employing statistical techniques as the guidance of investment has become a new trend in finance field. R software is providing us a scientific platform for effective investment. Using R software as a basic tool, this paper discusses in detail about the normality hypothesis of yields rate which plays a significant role in the portfolio selection theory by Harry Markowitz. Firstly, we conduct normal distribution fitting of the hypothesis through line chart, histogram, curve of kernel density estimation, curve of empirical distribution function, and QQ chart. Secondly, we verify the normality hypothesis by the Shapiro-Wilk test and the Kolmogorov-Smirnov test Finally we use the expectancy method and the exponential smoothing to make corresponding prediction, and arrive at the conclusion that the exponential smoothing is superior to the expectancy method.
