A study for each of 40 countries of the world found that there is a strong positive correlation (R2 = 62.9%) between the Life expectancy --average of men and women, in years-- (response variable) and the square root of the number of Doctors per person (explanatory variable) in the country. This seems to suggest that sending more doctors increases life expectancy. Perhaps, but let's look at another study set of data. For the same countries, there is a stronger positive correlation , (this time R2 = 72.5%), between the Life expectancy and the number of Televisions per person in each country. Should we conclude that increasing the number of TVs actually extends lifetimes? If so, we should send TVs instead of doctors to developing countries. Not only is the correlation with life expectancy higher, but TVs are much cheaper than doctors and possibly more fun.

A) Do you think strong correlation imply cause and effect?

B) What do you think is the key reason that's responsible for the high positive correlation in the study above?