The Dow Jones Industrial Average (DJIA) and the Standard & Poor's 500 Index (S&P 500) are both used to measure the performance of the stock market. The DJIA is based on the price of stocks for 30 large companies; the S&P 500 is based on the price of stocks for 500 companies. If both the DJIA and S&P 500 measure the performance of the stock market, how are they correlated? The following data show the daily percent increase or daily percent decrease in the DJIA and S&P 500 for a sample of nine days over a three-month period (The Wall Street Journal, January 15 to March 10, 2006).
DJIA .20 .82 -.99 .04 -.24 1.01 .30 .55 -.25
S&P 500 .24 .19 -.91 .08 -.33 .87 .36 .83 -.16