As the text explains, it can sometimes be very difficult to sort ...

[Kikoku]

As the text explains, it can sometimes be very difficult to sort out the direction of causality.
 
  a. Why might you think more police officers would lead to lower crime rates? Why might you think that higher crime rates would lead to more police officers?
  b. In 2012, the New England Journal of Medicine published research that showed a strong correlation between the consumption of chocolate in a country and the number of Nobel Prize winners in that country. Do you think countries that want to encourage their citizens to win Nobel Prizes should increase their consumption of chocolate?

Question 2

If the demand for the yen increases relative to the dollar, which of the following would occur?
 
  A) The dollar will depreciate. B) The demand for the dollar will increase.
  C) The yen will depreciate. D) The dollar will appreciate.

[helenmarkerine]

Answer to Question 1

a. There is a great deal of evidence that increasing the number of police officers in a neighborhood can drive down crime. The police, for example, will deter criminals who realize the chances they will be caught have gone up and the police may be able to head off conflicts between gangs. Therefore more police could lead to less crime. Cities strategically assign more police to high crime areas (since by definition, those are the areas where crimes are more likely to occur). Therefore, more crime can lead to more police.
b. Correlation does not necessarily imply causation. A strong positive correlation between chocolate consumption and Nobel Prize winners does not, by itself, suggest causation. It is possible that this is a chance correlation. It may also be case that certain variables that could explain this relationship have been omitted from the study.
See the June 11, 2013 New York Times article Chicago Tactics Put Major Dent in Killing Trend (http://www.nytimes.com/2013/06/11/us/chicago-homicides-fall-by-34-percent-so-far-this-year.html?hp) on the relationship between police and crime rates. See http://www.reuters.com/article/2012/10/10/us-eat-chocolate-win-the-nobel-prize-idUSBRE8991MS20121010 on the effects of eating chocolate.

Answer to Question 2

A