The Dow-Jones Industrial Average (DJIA) Index is a well-known stock index. The index was originally developed in 1884 and has been in place ever since as a gauge of how the U.S. stock market is performing. The file Dow Jones contains date, open, high, low, close, and volume for the DJIA for almost eight years of the trading days.
a. Assuming that the data in the file Dow Jones constitute the population of interest, what is the population mean closing value for the DJIA?
b. Using Excel, select a random sample of 10 days’ closing values (make certain not to include duplicate days) and calculate the sample mean and the sampling error for the sample.
c. Repeat part b with a sample size of 50 days’ closing values.
d. Repeat part b with a sample size of 100 days’ closing values.
e. Write a short statement describing your results. Were they as expected? Explain.