Transatlantic Trends is an annual survey of American and European public opinion (http://

trends.gmfus.org), with a random sample of about 1000 adults from each of 13 European countries each year. In 2006, 18% of Europeans expressed a positive attitude about President George W. Bush’s handling of international affairs. In 2014, 64% of Europeans expressed a positive attitude about President Barack Obama’s handling of international affairs.

(a) Explain what it would mean for these results to be based on (i) independent samples, (ii) dependent samples.

(b) If we compare results in 2006 and 2014, identify the response variable and the explanatory variable, and specify whether the response variable is quantitative or categorical.