Figure 8.31 shows the ACFs for 36 random numbers, 360 random numbers and 1,000 random numbers. a. Explain the dierences among these gures. Do they all indicate that the data are white noise? b. Why...

Figure 8.31 shows the ACFs for 36 random numbers, 360 random numbers and 1,000 random numbers.

a. Explain the dierences among these gures. Do they all indicate that the data are white noise?

b. Why are the critical values at dierent distances from the mean of zero? Why are the autocorrelations dierent in each gure when they each refer to white noise?