# Question: The quarterly sales data number of copies sold for a

The quarterly sales data (number of copies sold) for a college textbook over the past three years follow:

a. Construct a time series plot. What type of pattern exists in the data?

b. Use a regression model with dummy variables as follows to develop an equation to account for seasonal effects in the data. Qtr1 = 1 if quarter 1, 0 otherwise; Qtr2 = 1 if quarter 2, 0 otherwise; Qtr3 = 1 if quarter 3, 0 otherwise.

c. Based on the model you developed in part b, compute the quarterly forecasts for next year.

d. Let t = 1to refer to the observation in quarter 1 of year 1; t = 2to refer to the observation in quarter 2 of year 1; . . . ; and t = 12 to refer to the observation in quarter 4 of year 3. Using the dummy variables defined in part b and t, develop an equation to account for seasonal effects and any linear trend in the time series.

e. Based upon the seasonal effects in the data and linear trend, compute the quarterly forecasts for next year.

f. Is the model you developed in part b or the model you developed in part d more effective? Justify your answer.

a. Construct a time series plot. What type of pattern exists in the data?

b. Use a regression model with dummy variables as follows to develop an equation to account for seasonal effects in the data. Qtr1 = 1 if quarter 1, 0 otherwise; Qtr2 = 1 if quarter 2, 0 otherwise; Qtr3 = 1 if quarter 3, 0 otherwise.

c. Based on the model you developed in part b, compute the quarterly forecasts for next year.

d. Let t = 1to refer to the observation in quarter 1 of year 1; t = 2to refer to the observation in quarter 2 of year 1; . . . ; and t = 12 to refer to the observation in quarter 4 of year 3. Using the dummy variables defined in part b and t, develop an equation to account for seasonal effects and any linear trend in the time series.

e. Based upon the seasonal effects in the data and linear trend, compute the quarterly forecasts for next year.

f. Is the model you developed in part b or the model you developed in part d more effective? Justify your answer.

**View Solution:**## Answer to relevant Questions

Air pollution control specialists in southern California monitor the amount of ozone, carbon dioxide, and nitrogen dioxide in the air on an hourly basis. The hourly time series data exhibit seasonality, with the levels of ...Consider the following time series data: a. Compute MSE using the most recent value as the forecast for the next period. What is the forecast for month 8? b. Compute MSE using the average of all the data available as the ...The Football Bowl Subdivision (FBS) level of the National Collegiate Athletic Association (NCAA) consists of over 100 schools. Most of these schools belong to one of several conferences, or collections of schools, that ...Refer to the scenario described in Problem 16 and the file CreditScore. Partition the data into training (50 percent), validation (30 percent), and test (20 percent) sets. Predict the individuals' credit scores using a ...Suppose that IBM employs a network of expert analytics consultants for various projects. To help it determine how to distribute its bonuses, IBM wants to form groups of employees with similar performance according to key ...Post your question