Here are the number of domestic flights flown in each year from 2000 to 2012.
Year Flights
2000 ……… 7,905,617
2001 ……… 7,626,312
2002 ……… 8,085,083
2003 ……… 9,458,818
2004 ……… 9,968,047
2005 ……… 10,038,373
2006 ……… 9,712,750
2007 ……… 9,839,578
2008 ……… 9,378,227
2009 ……… 8,768,938
2010 ……… 8,702,365
2011 ……… 8,649,087
2012 ……… 8,446,201
a) Find the correlation of Flights with Year.
b) Make a scatterplot and describe the trend.
c) Why is the correlation you found in part a not a suitable summary of the strength of the association?
d) Find Kendall's tau for these data. Would that be an appropriate measure for summarizing their relationship? Explain.