(1) Discuss the difference between cross- sectional data and time series data.
(2) If we record the total number of cars sold in 2012 by each of 10 car salespeople, are the data cross- sectional or time series data?
(3) If we record the total number of cars sold by a particular car salesperson in each of the years 2008, 2009, 2010, 2011, and 2012, are the data cross- sectional or time series data?