The title above refers to the ‘Big Mac Index’, introduced by The Economist magazine. Essentially, part of McDonald’s marketing strategy is to offer familiar products everywhere in the world and therefore, the consumer knows what they are going to get from going to any McDonalds restaurant. The Big Mac burger can be seen as a constant good worldwide and consequently, is a convenient way to compare the purchasing power parity of different countries (basically how strong their currency is based on the price of a Big Mac).  Aside from being a homogenous good, this burger does seem to be an acceptable good to compare worldwide, because McDonalds restaurants are located almost everywhere in the world making the Big Mac easily accessible to many consumers and therefore a fairly accurate representation of countries worldwide. Also, the price of a Big Mac does reflect what the consumer is paying for the burger itself. Meaning that when a consumer goes to McDonalds, ambiance, customer service and other factors that may differ from country to country need not be included in the price of a Big Mac, because in general, consumers do not expect this from their McDonald’s experience.

http://www.economist.com/node/13055650