Social class can be measured unofficially by researchers or using official scales recognized by the government. An example of an official scale is the Registrar Generals scale, used in Great Britain from 1911 to 2000 and used by the government to measure social class. This model has been divided into two main classes, middle class and lower class. Each class was further broken down into separate categories depending on the individual's skill level. This system was relatively simple and easy to understand. However, the Registrar Generals scale was separated into classes based on profession and not individual, meaning that individuals who were wealthy and lived off investments or inheritances would be excluded from this particular scale and would not have a class position , this means that a scale is not a clear picture of everyone's position in society. Because the Registrar General's scale measures occupation and does not take into account people's views on their class position, for example, someone with a middle-class background may have a working-class job but may not consider themselves a worker.