Sociologists use the concept of occupational prestige (also known as job prestige) to measure the relative social-class positions people may achieve by practicing a given occupation. Occupational prestige results from the consensual rating of a job - based on the belief of that job's worthiness. The term prestige itself refers to the admiration and respect that a particular occupation holds in a society. Occupational prestige is prestige independent of particular individuals who occupy a job. Sociologists have identified prestige rankings for more than 700 occupations based on results from a series of national surveys. They have created a scale (with 0 being the lowest possible score and 100 being the highest) and then rank given occupations based on survey results. History People rate the ‘general standing’ of an occupation (the most common question). It is taken to be a measure of occupational prestige and hence of the social status of occupations. Many other criteria have been proposed, including ‘social usefulness’ as well as ‘prestige’ and ‘status’ themselves. In order to obtain the scale of occupations (which is invariably taken to be national in application), respondents' ratings are aggregated. Job prestige did not become a fully developed concept until 1947 when the National Opinion Research Center (NORC), under the leadership of Cecil C. North, conducted a survey which held questions regarding age, education, and income in regard to the prestige of certain jobs. This was the first time job prestige had ever been researched, measured, and taught. Duncan's Socioeconomic Index (DSI, SEI) became one of the most important outcomes of this survey, as it gave various occupational categories different scores based on the survey results as well as the result of the 1950 Census of Population. During the 1960s the NORC did a second generation of surveys which became the basis for the socioeconomic status (SES) score until the 1980s as well as the foundation for Trieman's International Prestige Scale in 1977. Out of these surveys and research job prestige has been defined in various ways. Some definitions include: The consensual nature of rating a job based on the collective belief of its worthiness. Prestige is the measurement of the "desirability" of an occupation in terms of socioeconomic rewards. Prestige reflects factual, scientific knowledge about the material rewards attached to certain occupations. Different people seem to weight these issues differently in their understanding of prestige. Most people seem to implicitly view