There are enormous differences between health-care systems in the United States and Canada. In a study to examine one dimension of these differences, 300 heart attack victims in each country were randomly selected. (Results of the study conducted by Dr. Daniel Mark of Duke University Medical Center, Dr. David Naylor of Sunnybrook Hospital in Toronto, and Dr. Paul Armstrong of the University of Alberta were published in the Toronto Sun, October 27, 1994.) Each patient was asked the following questions regarding the effect of his or her treatment:

1. How many days did it take you to return to work?

2. Do you still have chest pain?

The responses were recorded in the following way:

Column 1: Code representing nationality: 1 = U.S.; 2 = Canada

Column 2: Responses to question 1

Column 3: Responses to question 2–1 month after heart attack: 2 = yes; 1 = no

Column 4: Responses to question 2–6 months after heart attack: 2 = yes; 1 = no

Column 5: Responses to question 2–12 months after heart attack: 2 = yes; 1 = no

Can we conclude that recovery is faster in the United States?