Wexler adult intelligence scale.
An important feature of Wechsler intelligence scale is the use of biased IQ. The so-called biased IQ is the IQ expressed by the standard score, that is, each subject compares with people of the same age, unlike the IQ used in Biner scale before, but compares with people of different ages.
The Stanford-Biner Scale revised by 1960 also adopts biased IQ, so that every age has an average score, M= 100 and standard deviation σ = 16. The mean value of Wechsler Intelligence Scale for Adults and Children is 100, but the standard deviation is 15.
Therefore, a person's intelligence can be expressed by comparing with other people's test scores in the same age group. Take Wechsler Intelligence Scale as an example, its IQ calculation formula is:
Iq = 15(X-M)/S+ 100
Where x is the original score of subjects in a certain age group, m is the average score of the age group, and s is the standard deviation of the score of the group. (M-X)/S is the standard score, which is a relative quantity with standard deviation as the unit.