Question 13.33

13.33 AT&T wireline business.

With the continuing growth of the wireless phone market, it is interesting to study the impact on the wireline (landline) phone market. Consider a time series of the quarterly number of AT&T customers (in thousands) who have wireline voice connections.20 The series begins with the fourth quarter of 2011 and ends with the second quarter of 2014.

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  1. Make a time plot of these data. Describe the overall movement of the data series.
  2. Does there appear to be seasonality?
  3. Fit the time series with a linear trend model. Report the estimated model.
  4. Superimpose the fitted linear trend model on the data series. Does the fit seem adequate? If not, explain why not.

13.33

(a) The number of wireline voice connections has been steadily decreasing over this time period. (b) There is no seasonal pattern. (c) . (d) The data appear to curve rather than follow a straight line.