Address the following problem:
For the data of this exercise use the weighting constant a = 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?