What is an IQ Score?
Originally, IQ, or Intelligence Quotient, was used to detect persons of lower intelligence, and to detect
children of lower intelligence in order to place them in special education programs. The first IQ tests were
designed to compare a child's intelligence to what his or her intelligence "should be" as compared to the
child's age. If the child was significantly "smarter" than a "normal" child of his or her age, the child was
given a higher score, and if the child scored lower than expected for a child of his or her age, the child was
given a lower IQ score.
Today IQ testing is used not primarily for children, but for adults. Today we attempt to write tests that will
determine an adult's true mental potential, unbiased by culture, and compare scores to the scores of other
adults who have taken the
test. So today we compare an adult's objective results to the objective
results of other adults, and determine how intelligent each test taker is compared to all other test takers,
instead of comparing test takers to an arbitrary age related standard.
The first step to understanding IQ testing is to understand
Standard deviation is kind of the "avg of the avg," and often can help you find the story behind the data. To
understand this concept, it can help to learn about what statisticians call normal distribution of data.
A normal distribution of data means that most of the examples in a set of data are close to the "average,"
while relatively few examples tend to one extreme or the other.
Let's say you are writing a story about nutrition. You need to look at people's typical daily calorie
consumption. Like most data, the numbers for people's typical consumption probably will turn out to be
normally distributed. That is, for most people, their consumption will be close to the mean, while fewer
people eat a lot more or a lot less than the mean.
When you think about it, that's just common sense. Not that many people are getting by on a single serving
of kelp and rice. Or on eight meals of steak and milkshakes. Most people lie somewhere in between.
If you looked at normally distributed data on a graph, it would look something like this:
The x-axis (the horizontal one) is the value in question.
.. calories consumed, dollars earned or crimes
committed, for example. And the y-axis (the vertical one) is the number of datapoints for each value on the
.. in other words, the number of people who eat x calories, the number of households that earn x
dollars, or the number of cities with x crimes committed.