# Data forecasting cell phone case study

For the data of this exercise use the weighting constant = 0.5 and exponential smoothing to determine the forecast for 2005.

U.S. cellular phone subscribership has been reported as shown below for the 1993-2004 period

Year Subscribers (millions) Year Subscribers (millions)

1993 16.0 1999 86.0

1994 24.1 2000 109.5

1995 33.8 2001 128.4

1996 44.0 2002 140.8

1997 55.3 2003 158.7

1998 69.2 2004 182.1

a. fit a linear trend equation to the time series. Using the equation, determine the trend estimate for 2010

b. fit a quadratic equation to the time series, then use the equation to determine the trend estimate for 2010

c. construct a graph of the time series along with the equations fitted in parts (a) and (b). Which equation appears to better fit the data?

https://brainmass.com/statistics/time-series-analysis/linear-trend-time-series-212521

#### Solution Preview

For the data of this exercise use the weighting

For the data of this exercise use the weighting

For the data of this exercise use the weighting constant = 0.5 and exponential smoothing to determine the forecast for 2005.

U.S. cellular phone subscribership has been reported as shown below for the 1993-2004 period

Year Subscribers (millions) Year Subscribers ...

#### Solution Summary

Linear trends on a time series plot are examined. An equation is used to estimate the trends.