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The following essay will delve into the development, reliability, and validity of the IQ test. IQ tests are multi-faceted and have channeled into various levels of human intelligence and psychological traits. Therefore, this essay will specifically deal with the area propagated by Binet and his colleagues. The most widely used tests by psychologists both in schools and in health settings is the Stanford-Binet test. This test is the modern version of a test devised in the early 1900 s by Binet and Simon at the request of the Paris school system. There purpose was to identify children who were unable to learn in traditional classroom settings.
Binet and Simon believed that intelligence was malleable and that childrens academic performance could be improved with special programs. They took an innovative approach to the construction of their test, Binet and Simon asserted that to differentiate among individuals, one had to sample higher mental functions such as comprehension, reasoning, and judgement. They developed an array of intellectual tasks involving such things as the ability to attend to something and the ability to recognize logical absurdities. In addition, Binet and Simon recognized and built into their test the chronology of childrens learning. Therefore, as children grow older they are able to solve increasingly complex problems. In later revisions, based on the criterion that any test item must effectively sort children by age, Binet and Simon selected items to reflect childrens competence at different age levels.
In refining their tests, Binet and Simon administered aptitude question to large groups of children whose teachers had identified them as either bright or dull. The knowledge gained by the aptitude questions allowed Binet and Simon to differentiate between these two groups. Binet originated the concept of mental age, which is an index of a childs actual performance level in contrast to their true age. The mental age concept was later superseded by the intelligence quotient, for which the following formula was devised: IQ = MA/CA x 100. Therefore, the ratio IQ was formed by expressing the childs age in months, dividing it into the mental age in months, and multiplying it by a factor of 100. For example, a child of chronological age 7 and mental age 7 would therefore have an IQ of 100.
The ratio IQs were distributed more or less normally, with standard deviations in the neighborhood of 15 or 16. About 46 per cent of the population had IQs in the range of 90 - 109, about 4 per cent above 130, and about 3 per cent below 70 as the table below conveys. Percentage Distribution of IQs IQ Standardizing sample (N = 2904) High School Graduates (N = 21, 597) College entrants (N = 1093) 140 and above 1. 3 12. 6 31. 7 130 - 139 3. 1 120 - 129 8. 2 110 - 119 18. 1 22. 8 46. 1 100 - 109 23. 5 29. 9 18. 1 90 - 99 23. 0 2 80 - 89 14. 5 22. 7 14. 3 70 - 79 5. 6 Below 70 2. 6 The converted scores are standard scores, the intelligence quotient conversion fixes the mean at 100 and the standard deviation at 15 or 16. A person whose raw score is 2 standard deviations above the mean for his age is assigned an IQ of 130.
The IQ scale is out dated; scores of this form have no advantage over standard scores expressed on the 50 +/- 10 scale. The only justification for the 100 +/- 15 scale is that intelligence quotients have been used in the psychological literature for many decades, so that a body of learning had grown up about what can be expected of a child with IQ 60 or IQ 120. Normal Curve of Standardized IQ Scores There was a study done to test the effect of variations in standardization of IQ scores. The research studied the effects of the Pictorial Test of Intelligence, Stanford-Binet, and the Wechsler scales. This test was standardized on a small but apparently representative sample of children.
The results were: Mean s. d. PTI 114 8 (Pictorial Test of Intelligence) SB 114 18 (Stanford-Binet) WISC 102 10 (Wechsler Scales) This group of children was not randomly selected, therefore it is surprising that the data does not show a mean of 100 s. d. 16. Such inconsistencies are often found when different tests areas are compared.
The principal conclusion, is that an intelligence quotient in isolation can be given only a very rough interpretation. One cannot conclude that an IQ of 130 on one test represents the same degree of superiority as an IQ of 130 on another. Individual IQ tests have reliability between 0. 90 and 0. 95. However, there are fluctuations with age in the size of the standard deviations of conventional IQs for the Stanford- Binet scales. Resulting in varying concentrations of average difficulty item at different levels of the test.
Consequently, IQ scores obtained with these scales must be corrected if they are to have consistent meaning from one age to another. When corrections are applied only at those ages at which the vari abilities are the most out of line, the fluctuations in the mean IQs for the sample increases rather than decreases. However, when the age change in variability is taken into account at each age by transforming the conventional IQs into deviation IQ s, the range of changes in mean score is reduced by half. Therefore, there is a need for standard scores or deviation IQs for the Stanford-Binet scales. The standard error of measurement of the Stanford-Binet IQ, is 5 IQ points. Thus a person who scores an IQ of 100 +/- 5 would have a true IQ range from 95 - 105.
There is not much confidence that any two persons whose IQs differ by less than about 10 points truly differ in the intelligence measured by the IQ test. It should be noted again that the standard error of measurement for a given mental age score is not a constant for all chronological ages. Since there is a general increase with age in reliability of performance on an item, the standard errors of measurement for a given mental age score tend to decrease in magnitude for older subjects. This increase in reliability with age, based on test-retest data, appears to be chiefly a function of the decline with age in the rate of mental growth between birth and maturity. The stability coefficients for a one year interval average is close to 0. 90, being slightly lower at younger ages (below 6 years) and slightly higher at older ages. The average change in IQ (either up or down) over a one year interval is about 7 points.
The IQ maintains considerable year-to-year stability for most persons and shows large changes for relatively few persons, with fewer than 1 percent showing changes as great as 20 or more points. Furthermore, other longitudinal studies indicate that the greater the interval between tests, the greater the tendency is for the individual child to shift in relative position from their original IQ. Which indicates that there is a greater constancy of relative standing with increasing age. The intelligence quotient shows significant correlations with more other variables of educational, occupational, and social importance than any other currently measurable psychological trait. Hence, no other items of information that is obtainable about a child will predict their overall learning ability and academic achievement in school, better than scores on a recently administered IQ test. This is not because the IQ tests measure only what the child has learned in school, but it also measures a general cognitive ability that plays is an important part in scholastic progress more than any other trait.
At any one point in time, a single IQ test will usually correlate anywhere between 0. 50 and 0. 80 with scholastic achievement, as assessed by standard achievement tests. If IQs and achievement scores are obtained at each grade level and averaged over three to five years, the correlation between them approaches 0. 90, or near the overall reliability of the IQ test. The correlation between IQ and teachers grading system is generally 0. 10 to 0. 20 lower than the correlation of IQ with achievement test scores. In general, the validity of IQ for predicting academic achievement decreases at higher levels of schooling.
The most typical validity coefficients are as follows: Elementary school 0. 60 - 0. 70 High School 0. 50 - 0. 60 College 0. 40 - 0. 50 Graduate School 0. 30 - 0. 40 Furthermore, in the case of IQ and academic achievement at each more highly selective level of education there seems to be a lower correlation. For example, IQs above 115 are the bright and exceptional pupils in the top groups in elementary school. But IQs of 115 are near the bottom of the distribution of students in graduate school. The relationship between IQ and learning ability is not the same for all types of learning.
Learning is more highly correlated with IQ under these conditions: 1. When learning is intentional and the task calls forth conscious mental effort and is paced in such a way as to permit the subject to think. 2. When the material to be learned is hierarchical, in the sense that the learning of later elements depends on mastery of earlier elements 3. When the learning task permits transfer of knowledge or skills form somewhat different but related past learning. 4.
When the learning material is age-related. 5. When the amount of time for learning a given amount of material is fixed for all students All these conditions influence the correlation between learning and IQ, and all are highly characteristic of intensive school learning. Peoples prestige rankings of occupations or other signs of occupational status show a correlation with IQs of individuals in the various occupations of about 0. 50 to 0. 60 for young men (ages 18 to 26) and of about 0. 70 for men over 40. So-called tests of creativity show as much or more correlation with IQ as with other so- called tests of creativity.
There are also a number of physical correlations of IQ: brain size (correlation about 0. 30), brain wave (correlation of 0. 30 to 0. 50), stature (correlation of 0. 10 to 0. 30), basic metabolic rate in childhood, obesity (negative correlation), and nearsightedness (correlation about 0. 25 in favor of myopes). The IQ test may be exceptional in many ways but it has its faults as well. The IQ arose out of the idea that a childs rate of mental development reflects their potentiality. It was thought that a 4 year old who has mental age 5 is developing 25 per cent faster than the average, and will continue to develop at this faster rate until adulthood. This implied that for any given child the plot of mental age in successive years forms an ascending straight line.
Any linear trend obviously breaks down in adulthood. Mental test scores of adults are very little higher than those of adolescents. Since the average score at age 40 is about the same as at 15, it makes no sense to refer to someone as having reached mental age 40. Many critics feel intelligence tests are unfair when evaluating children in minority groups.
Most critics feel that the tests are based on skills and knowledge deemed important by the majority culture. Children from minority homes might not share the same values or have access to the same knowledge that middle-class children do, making the test culturally biased. Moreover, there has been a great evolution in the original ways of IQ testing for example Wechsler has built a scale for adults, introducing the deviation IQ where a 40 year old with IQ 125 does not match the average 50 year old. Instead, the deviation IQ reports his standing among other of his own age. In conclusion, the impact of the psychometric assessment has been most strongly expressed in the IQ test. IQ tests allow us to assess the intellectual abilities relative to a normative population.
There are many factors that have determined the tests reliability and vast use mentioned above. It is no wonder that this test is as widely used today as it was when it was first developed. Thus, many institutions, schools, teachers, and children have benefitted from the usefulness of the tests results. 30 c
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