Question 13.58

13.58 CTA commuters.

The Chicago rapid transit rail system is well known as the “L” (abbreviation for “elevated”). It is the third busiest system after the New York City Subway and the Washington Metro. Consider the daily count of commuters going through a particular station. The count is based on how many commuters went through all the turnstiles at the station. In particular, the data are for the downtown station of Randolph/ Wabash from April 7, 2014 (Monday), to May 11, 2014 (Sunday).33

cta

  1. Make a time plot of the commuter series. Describe any important features of the time series.
  2. Use the moving-average approach to compute seasonal ratios and report their values. Be careful to recognize that the number of seasons (days) is odd.
  3. Produce and plot the seasonally adjusted series. What are your impressions of this plot?
  4. Fit a trend model and report the -value of the trend coefficient? Is there enough evidence of the presence of trend?
  5. Given your conclusion of part (d), forecast the number of daily commuters going through the Randolph/ Wabash for each of the seven days of the week.