New York Times reporter Mark Bittman wrote: “A study published in the journal PLOS ONE links increased consumption of sugar with increased rates of diabetes by examining the data on sugar availability and the rate of diabetes in 175 countries over the past decade. And after accounting for many other factors, the researchers found that increased sugar in a population’s food supply was linked to higher diabetes rates independent of rates of obesity” (2013; opinionator.blogs. nytimes.com/2013/02/27/its-the-sugar-folks/). 

a. Explain how the researchers may have used multiple regression to analyze these data. 

b. Why did Bittman emphasize that the researchers accounted for many other factors? 

c. List at least three other factors that the researchers may have included. 

d. Bittman also wrote: “In other words, according to this study, obesity doesn’t cause diabetes: sugar does. The study demonstrates this with the same level of confidence that linked cigarettes and lung cancer in the 1960s.” Explain in your own words why Bittman likely feels justified in drawing a causal conclusion from correlational research.