Exam 18: Models for Time Series and Forecasting

Quarterly sales The quarterly sales (in millions of dollars)of a department store chain were recorded for the years 1997-2000.They are listed below. Year Quarter Sales 1997 1 21 2 36 3 28 4 44 1998 1 25 2 23 3 39 4 36 1999 1 30 2 41 3 47 4 55 2000 1 34 2 29 3 32 4 48 -Calculate the four-quarter centered moving averages.

The Consumer Price Index (CPI)describes the change in prices from one time period to another for a fixed "market basket" of goods and services.

The monthly seasonal index for August is 101.The de-seasonalized August output is 250,000 units.What is the annual output? Remove all commas from your answer before submitting.

For five years of data,compute a linear trend equation and forecast the value for the sixth year.Code the years 0 through 4.The data values are: 27,32,28,37,and 38. $\hat{ Y }$ = ____________________ sixth year value = ____________________

Distinguish between the four components of a time series.Define each component.

Why do we examine time series?

The effect that business recessions and prosperity have on time series values is an example of the:

Table - 5 -8 3 2 4 6 -9 3 -5 -2 -0.4 3 10 0.3 - 16 18 21 -4 -2 10 13 -20 -8 15 19 -8 -6 -1 -What is the computed value of the Durbin-Watson statistic?

Gashol (a mixture of gasoline and methyl alcohol)sales in Iowa City have been recorded over the past 10 months as shown below: Manth Jan Feb Mar Apr May June Juy Aug Sep Oct Sales 75 72 81 92 90 105 112 107 110 93 -Compute the five month moving average.

A time series can be deseasonalized by using the ____________________ for the respective months or quarters of the year.

Inventory The following values are the means for each month of the inventory as a percentage of the moving average for the twelve months of the year. 79 86 101 104 112 113 115 110 97 99 93 86 -Compute the seasonal index for February.

Second-order autocorrelation is the correlation between e_t and e_t-2.

Avalon Convenience Store Daily sales volume from the Avalon Convenience Store is shown in the table below. Day Sales () 1 512 2 328 3 538 4 662 5 498 6 546 7 579 8 595 9 616 10 655 -What is the linear trend equation?

Which method would you recommend to your statistics professor in selecting the appropriate forecasting model if avoiding large errors is extremely important to him or her?

Compared to the Mean Squared Error approach,the Mean Absolute Deviation places a greater penalty on estimates for which there is a large error.

In general,the most important component of most time series is the

A common method of testing for autocollinearity (serial correlation)is a Wilcoxon matched pairs signed rank test.

Which of the following statements is not true?

Which of the following equations de-seasonalize a time series?

If summer 2003 sales were $12,600 and the summer seasonal index was 1.20.What is the de-seasonalized 2003 summer sales value? Remove all commas from your answer before submitting.