William Stern-German psychologist who developed the formula for
intelligence quotient (IQ); [mental age/chronological age] X 100 =
IQ
General intelligence (g)-general ability that Spearman and
others believed underlies specific mental abilities and is
therefore measured by every task on an intelligence test.Factor
analysis was invented nearly 100 years ago by psychologist Charles
Spearman, who hypothesized that the enormous variety of tests of
mental ability--measures of mathematical skill, vocabulary, other
verbal skills, artistic skills, logical reasoning ability,
etc.--could all be explained by one underlying "factor" called "g
factor or general intelligence factor."
Intelligence testing was gaining popularity in America, and it
became the bread-and-butter for many early psychologists. Although
Lewis Terman later supplanted Goddard as the authoritative voice on
intelligence testing, it was Goddard who created the intelligence
testing industry. Thus, he's responsible for popularizing
psychological science in America and providing psychology
practitioners with their chief assessment tool.