•In reality, by the time the Globe released the poll, it contained old information from January 2–6, 2010. Even more problematic was that the poll included people who said that they were unlikely to vote!
16Example 3•Starbucks Corp., the world’s largest coffee-shop operator, reported that sales at stores open at least a year climbed 4% at home and abroad in the quarter ended December 27, 2009. Chief Financial Officer Troy Alstead said that “the U.S. is back in a good track and the international business has similarly picked up. … Traffic is really coming back. It’s a good sign for what we’re going to see for the rest of the year” (, January 20, 2010).
17Problem with conclusion•In order to calculate same-store sales growth, which compares how much each store in the chain is selling compared with a year ago, we remove stores that have closed. •Given that Starbucks closed more than 800 stores over the past few years to counter large sales declines, it is likely that the sales increases in many of the stores were caused by traffic from nearby, recently closed stores. In this case, same-store sales growth may overstate the overall health of Starbucks.
18Example 4•Researchers at the University of Pennsylvania Medical Center found that infants who sleep with a nightlight are much more likely to develop myopia later in life (Nature, May 1999).
19Problem with conclusion•This example appears to commit the correlation-to-causation fallacy. Even if two variables are highly correlated, one does not necessarily cause the other. •Spurious correlation can make two variables appear closely related when no causal relation exists. •In a follow-up study, researchers at The Ohio State University found no link between infants who sleep with a nightlight and the development of myopia (Nature, March 2000).
20Statistics•….. is the methodology of extracting useful information from a data set.
21Statistics•….. is a way of reasoning, along with a collection of tools and methods, designed to help us understand the world.