Remi Pearce, of Ilam Primary School, asks :-
How do you know the IQ of a person?
Basil O'Connor, a retired psychologist, responded.
A scientist knows the IQ of a person by the scores obtained from an intelligence test. I usually gave two tests for greater accuracy.
The first test was in the form of multiple choice questions about parts missing from geometrical patterns. The second, more comprehensive, test used questions based on general knowledge, comprehension, memory, reasoning ability and practical problems such as jigsaws. In each section the problems became progressively more difficult.
In either case the person is assigned an IQ by comparing their performance with that of people of a similar age. Tables of the latter are available to psychologists.
A single number is not very meaningful so the person is usually given the grouping in which their scores belong, for example Low Normal, Average, Bright Normal, Superior etc., as well as measured strengths and weaknesses.
Better still, several IQ's are measured. For example, Verbal IQ from tests involving word problems, Practical IQ from tests involving both hands and brain and General IQ.
This is all rather like judging people on their sporting ability by judging their ability at several sports then giving an overall grade and comparing that grade with all other people of the same age.