Across nine European countries in a large-scale survey, people had a hard time identifying signs of a stroke or heart attack. The survey1 included 10,228 inhabitants of Austria, France, Germany, Italy, the Netherlands, Poland, Russia, Spain, and the United Kingdom. Participants ages ranged from 14 to 98 . Of those surveyed, less than half ( 4910 ) linked arm or shoulder pain to heart attacks. Use StatKey to find a 99 % confidence interval for the proportion of Europeans (from these nine countries) who can identify arm or shoulder pain as a symptom of a heart attack.