We collected data on real income for 2009; however, we did not do the same for 2007. Therefore, we cannot compare changes in real income because we are missing necessary information regarding real income from 2007. If there was indeed a change in real income between the two years, our data would be compromised because the magnitude of the effects of income on necessary expenditures would be inaccurate. Therefore, we assume that real income does not change between the two years in order to meaningfully compare our data.
