Exam 18: Time Series and Forecasting

Product sales since 2001 are: The least squares trend equation is given as: Ŷ = 100 + 28t, where t is set equal to 1 for 2001. What were the predicted sales for 2009?

Given a linear time series trend Ŷ = 5.2 + 3.1t, what is the forecast for 2010 if the time series started in 2003?

When the data is divided by the seasonal indexes, the ____________ is removed from a time series.

To calculate quarterly typical seasonal indexes, how many periods are included in the ratio-to-moving-average method?

The _____________ method is useful in smoothing out a time series.

If a quarterly seasonal index is 0.56, it implies that:

The range of possible values for the Durbin-Watson statistic is:

In the linear trend equation, Y = a + bt, the coefficient b represents ___________.

If time series data are plotted on graph paper having an arithmetic scale that increases or decreases by equal percents, what type of graph will it be?

A resort hotel performed a quarterly time series analysis for demands over the last five years (periods 1 through 20). The analysis resulted in the following trend equation and seasonal indexes: Ŷ = 1000 + 150t Based on the seasonal indexes, which quarter is expected to have 20% less demand than predicted by the trend line?

A plastics manufacturer performed a quarterly time series analysis for demands over the last five years (periods 1 through 20). The analysis resulted in the following trend equation and seasonal indexes: Ŷ = 920.0 + 22.6t The seasonal indexes sum to 4.0. Therefore, the indexes have been _________.

A time series is a collection of data that _______________.

Which of the following statements about autocorrelation are true? I. Successive residuals are often correlated in time series because an event in one time period often influences the event in the next period. II) If residuals are correlated, we can use r as the coefficient of correlation and conduct the common tests of hypothesis about regression coefficients. III) A Durbin-Watson statistic d is used, instead of directly conducting a hypothesis test on r.

Product sales since 2001 are: The least squares trend equation is given as: Ŷ = 100 + 28t, where t is set equal to 1 for 2001. On average, how much did sales change per year from 2001 to 2009?

The forecast for the third quarter is 1,000 units; the seasonal index for the quarter is 0.85. What are the seasonally adjusted sales for the quarter?

A typical sales index of 96 for January indicates that sales are ____________________.

The trend forecast equation is Ŷ = 100 + 120t. The next forecast is for period 11. The typical seasonal index for period 11 is 1.25. What are the forecast sales for period 11?

A resort hotel performed a quarterly time series analysis for demands over the last five years (periods 1 through 20). The analysis resulted in the following trend equation and seasonal indexes: Ŷ = 1000 + 150t Using the trend line equation and the seasonal indexes, predict demand for the third quarter of the next year .

Autocorrelation occurs when successive residuals are _________.