Exam 18: Time Series and Forecasting

The ________ of the adjusted seasonal indices equals one.

Noncausal forecasting models are purely time series models in the sense that the forecasts are made based only on historical data concerning the variable of interest.

When the forecasting method of seasonal dummy variables is applied on a quarterly time series,four dummy variables are needed.

Which of the following is a similarity between the exponential smoothing method and the moving average method?

Using the decomposition model y_t = T_t × S_t × I_t ,forecasts are made by _______,where and represent the estimated trend and the (adjusted)seasonal index for period t,respectively.

Quarterly sales of a department store for the last seven years are given in the following table. The Excel scatterplot shown indicates that the quarterly sales have an increasing trend and seasonality.Therefore,the linear regression model,Sales = β₀ + β₁Qtr1 + β₂Qtr2 + β₃Qtr3 + β₄t + ε,with three seasonal dummy variables Qtr1,Qtr2,and Qtr3,and the decomposition method are proposed to make sales forecasts.For the regression model,the following Excel partial output is available. Using the regression equation for the linear trend model with seasonal dummy variables,what is the sales forecast for the fourth quarter of Year 8?

Which of the following models is considered for a quarterly time series that seems to change on average by a fixed amount and seems to have seasonality?

Based on quarterly data collected over the last five years,the following regression equation was found to forecast the quarterly demand for the number of new copies of a business statistics textbook: = 2,298 - 6635Qtr1 - 1,446Qtr2 + 303Qtr3 + 26t,where Qtr1,Qtr2,and Qtr3 are dummy variables corresponding to Quarters 1,2,and 3,and t = time period. For a given year,the demand in Quarter 3 is on average _________.

Although we use the MSE to compare the linear and the exponential trend models,we cannot use it to compare the linear,quadratic,and cubic trend models.

Which of the following factors refers to quantitative forecasting methods?

The moving average method is one of the most complex smoothing techniques used for processing time series.

Causal forecasting models are based on regression framework,where the variable to be forecast depends on one or more explanatory variables.

If T denotes the number of observations,which of the following equations represents the one-step-ahead forecast for the model y_t = β₀ + β₁x_t + ε_t?

Smoothing techniques are suitable for use when forecasts need to be updated frequently due to new observations that become available.

The mean of the absolute residuals defines the _________.

Which of the following is not an example of a time series?

Which of the following components does not cause the systematic patterns?

When a time series has both trend and seasonality,moving averages can be employed to separate the effect of these two components.

When a time series is analyzed by the model y_t = T_t × S_t × I_t ,which of the following is valid?

Prices of crude oil have been steadily rising over the last two years (The Wall Street Journal,December 14,2010).The monthly data on price per gallon of unleaded regular gasoline in the United States from January 2009 to December 2010 were available.Three trend models were created,and the following relevant information became available. Which of the following is a cubic trend equation used to forecast for the price of regular unleaded gasoline?