The average variability of all the scores will be 15 meaning the interval between one and measure, and the next is 15.Measurement of IQ in this study will use the interval scale of measurement. Measurement of scale is appropriate because the IQ test satisfies the identity, magnitude and equal intervals properties of scale measurements. The scores in an IQ lack a true zero point. The IQ test utilizes and interval scale because we have intervals. The test forms a bell curve that has one standard deviation either 15 points higher or lower than 100. Therefore, the interval from one IQ level to the next is the same, 15 points. We can tell if a person’s IQ is greater than the other, equal to or less than another person’s IQ. For instance, a person with an IQ score of 110 is 40 points greater than a person with an IQ score of 70. However, it is scientifically not right to say that a subject with an IQ of 120 has twice the intelligence of another with an IQ score of 60 (Tip amp. Laurence, 2011).