(Makeup for missed discussion on November 10th)
People are always interested in their level of intelligences and IQ tests are one of the most common ways to measure it. In my opinion, IQ tests are not very reliable in that everyone can score differently in different times if they prepare themselves for the questions. Also, it is about the frequency of using the brain. I mean if you read book, play sudoku, etc very often, then you are more likely to score higher on the IQ test than other people can.
Moreover, this issue has a close relationship with socio-economical status: If one is grew up in a financially poor area, then he/she is more likely to score lower then a person who is well educated. However, the thing is if you take that less-educated person and train him, then he can score better each time he tries harder.