Population density is not random. People live where they can support themselves. And a number of factors contribute to the pattern worldwide population distribution. Among them are physical, historical, economic, political and cultural factors. But, students comparing population density figures cited in the sources they are using, often tend to draw erroneous conclusions. For example, Bolivia and Saudi Arabia are both sparsely populated. In turn, Bangladesh and Belgium are both densely populated, but that is where the similarity ends. Bolivia and Bangladesh are both extremely poor, while Saudi Arabia and Belgium, by comparison, are very wealthy nations. Thus, by themselves the density figures are largely meaningless. Students should be aware of this, and be cautioned to make certain that when doing their research that they are comparing "equals" in the true sense of the word.