The commodity school appears to make the assumption that the various category definitions are applicable across all cultures. Unless the definitions are refined, this is not necessarily true. First, let us take into account income and the state of the economy. Depending upon one’s income or the current state of the economy, the various category definitions, as most recently proposed by Murphy and Enis, are probably not applicable. For example, the term ‘effort’ is used in the definitions of convenience, preference and specialty products. The word effort means the total work done to achieve a particular end. This implies that the effort expended to purchase and product would not simply include the decision-making process. If someone is of modest means, total purchasing effort may require walking to the store, in all sorts of weather, sometimes at great distances to obtain the so-called convenience product. In addition, people of modest means may place much greater importance on the selection of convenience products than individuals of greater wealth to make sure they are getting the most value for their hard-earned money. This would be more in line with the economic theory that consumers are value maximisers.