Many professional sports are arguing that they need a new stadium to be competitive, as newer stadiums can bring in more fan revenue which can in turn allow teams to buy more expensive players. Some major league baseball teams have built new stadiums in the past decade. Consider the attendance (in millions) in the last year of the old stadium and the first year of the new stadium. Using a sample of 5 randomly selected teams, researchers would like to determine if there is any evidence that attendance levels differ between using old vs new stadiums. The data for these five teams are shown below: Team Attendance (in millions)
Old Stadium New Stadium
Cincinnati Reds 1.9 2.4
New York Yankees 4.3 3.7
Philadelphia Phillies 2.3 3.3
Seattle Mariners 2.7 2.9
Washington Nationals 1.9 2.3

Required:
a. Calculate the test statistic appropriate to the correct statistical method.
b. Suppose all assumptions were satisfied for valid inference, and the researcher found a statistically significant lower average attendance in the new stadium compared to the old stadium. (This does not mean that this data support this conclusion - this is just hypothetical.) Does this mean that the new stadium caused attendance to decrease? Why or why not?