Researchers wanted to determine if there was an association between daily pomegranate consumption and the occurrence of high cholesterol. The researchers looked at 94,059 women and asked them to report their pomegranate-eating habits. The researchers also determined which of the women had high cholesterol. After their analysis, the researchers concluded that having two or more servings of pomegranate per day was associated with a reduction in high cholesterol.

(a) What type of observational study was this? Explain.

(b) What is the response variable in the study? Is the response variable qualitative or quantitative? What is the explanatory variable?

(c) In their report, the researchers stated that “After adjusting for various demographic and lifestyle variables, daily consumption of two or more servings was associated with a 30% reduced prevalence of high cholesterol”. Why was it important to adjust for these variables?