1. Quarterly time-series data with a trend can be applied to models that assume stationary data by?

a. Averaging the data over time

b. taking the first difference of the original series

c. taking the forth difference of the original series

d. using a moving average

2. Which of the following is appropriate for testing the null hypothesis of zero autocorrelation at lag k t the approximate 95 percent level.

a. reject null hypothesis if [rk] > 1/SQRT(n)

b. reject null hypothesis if [rk] > 2/SQRT(n)

c. reject null hypothesis if [rk] < 1/SQRT(n)

d. reject null hypothesis if [rk] < 2/SQRT(n)