Marketing (the Super Bowl)

It has been observed in the past that when an AFC team wins the Super Bowl, the stock market rises in the first quarter of the year in almost every case. When an NFC team wins the Super Bowl, the stock market falls in the first quarter in most cases. Does this mean that the direction of movement of the stock market is caused by which conference wins the Super Bowl? What does this example illustrate? What purpose does multiple regression analysis serve? Give an example of how it might be used in marketing research. How is the strength of multiple regression measures of association determined?