|
Below are brief explanations of the technical aspects of some of the more complicated terms used in IQ testing, specifically the terms I used on the history page. Much of intelligence testing, and all psychometrics, deals with complicated statistics techniques that take entire college courses to explain. However, I will only present basic concepts here. Before the the advent of deviation IQ in the 1960 revision of the Stanford-Binet IQ test, the IQ test used a simple concept of taking an individual's derived mental age (MA), dividing it by their chronological age (CA), and multiplying the result by 100 (so the result wouldn't be a decimal). The math is shown below: MA ---------- X 100 = IQ CA Linear regression is the process of fitting a line to a scatter plot of data points. The line is then used to predict where future data points will lie. Future values of the independent variable (the variable the experimenter controls) are compared with the equation of the line to predict what the value of the dependent variable (the one the experimenter measures) will be. The figure below is a sample scatter plot with a regression.
The standard deviation is a statistical measure that approximates the average amount that measurements differ from the mean score of all the measurements. It is computed by taking each individual score and subtracting the mean score from it, then totaling the results of all these subtractions. This sum is then squared and then divided by the number of scores. This result is known as the variance. Taking the square root of the variance results in the standard deviation ( s ).
s
= The bell curve is a method of comparing a distribution of scores by comparing frequencies (which can be thought of as the amount of times each score appears) of scores over the full range of scores (from the lowest score to the highest score). The curve is symmetrical about the mean of the all the scores. The curve is divided into sections, each section being a certain number of standard deviations away from the mean. The area under each section represents a certain percentage of the total area under the curve, and the more standard deviations away from the mean a section is, the less area is under it (as shown on the diagram below). Since the area in this case represents the percentage of people within a given range of IQ scores, this means that the further away from the mean IQ score (100) an individual is, the less people there are with the same IQ score. The bell curve represents the fact that most people fall near the mean IQ of one hundred, and that there are few people with extremely high or low IQs. The bell curve can be applied to all kinds of measurements, such as height and weight, not just IQ. (Except for the the bell curve, all of the diagrams and figures on this page were made by me) |
Created by Chris Riedel, January 2002 Designed for Mrs. Hannah's AP Psychology Class, third period, at Thomas Jefferson High School for Science and Technology |