Introduction to Sampling Theory Population and Random Sample Population and Random Sample Example 3 (6.3).[S&P 500 price index] Let Xi be the return on S&P500 price index at day i,from January 4,1960 to December 31,2010.Then XT=(X1,.. .Xn)forms a random sample with size n 12839. The observed data set x"=(x1,..,xn),depicted in Figure 6.2,is a realization of the random sample X". 0.10 S&P500日收益率 0.05 0.00 0.05 -0.10 Figure 6.2 0.15 0.20f 19601965197019751980198519901995200020052010 Introduction to Sampling Theory Introduction to Statistics and Econometrics April 16,2020 8/167Introduction to Sampling Theory Introduction to Sampling Theory Introduction to Statistics and Econometrics April 16, 2020 8/167 Example 3 (6.3). [S&P 500 price index] Population and Random Sample Population and Random Sample Figure 6.2