Showing posts with label IQ scores. Show all posts
Showing posts with label IQ scores. Show all posts

Saturday, October 30, 2021

Average Intelligence

 


The concept of average intelligence is sometimes difficult to appreciate because the two words, average and intelligence, are sometimes not defined.

Average 

To psychologists and counselors who administer tests of intelligence, a person who scores at the 50th Percentile has average intelligence as defined by the number of correct answers to test tasks compared to others in their age group.

Many tests set the middle score at 100 thus, 100 = average intelligence on many tests.

All test scores vary from time to time so, a person may earn more or less points on another day. This fluctuation is estimated and can range for example by plus or minus 3-5 IQ points depending on the test and age group.

 If you retake the test in a month or so, you may score better because of the “practice effect”—you’ve seen the items recently so you will probably do better.

There is an average range so examiners will not focus on the obtained score but consider a broader range. For example, some may consider 90 to 110 as average. Some use a statistic called the standard deviation, which is often 15 points on an IQ test. If a clinician uses a Standard Deviation of 15 points then the average range of intelligence scores = 85 to 115 (that is plus or minus 15 points from 100). Statistically, about 68% of people earn scores in this broad average range thus, most people in a given age group and the same population, will have an IQ score or scores in this broad average range.

By this definition, people who are above average intelligence earn scores above 115 on tests. In the US, schools often considered scores at 130 or higher as gifted but other tests and reports are considered. Also, people who scored below 85 were considered below average intelligence. Depending on their other abilities, they may need assistance with school work or work tasks. People with high and low scores are different so broad statements can be misleading.

Intelligence 

There are different theories of intelligence and tests have been constructed based on a few of the theories. Clinicians should be able to tell you basic facts about the test you or your child/loved one took. For the most part, the best tests ask examinees to answer a variety of questions and solve different types of problems. Thus, the best tests sample a variety of problem-solving tasks and average the scores for the different types of tasks.

For example, the ability to define words is one common measure of verbal intelligence. Through many years, examiners have found what people know in different age groups.

An example of performance intelligence is solving puzzles using blocks with different designs, which can be arranged to match pictures on a card. This ability increases considerably from preschool to adulthood.

There are other types of intelligence like emotional intelligence and social intelligence. Clinicians have developed tests to measure these skills too.

In a sense, intelligence is what is measured by intelligence tests—that’s circular—but it does give people a sense of what people know how to do compared to their age peers.

In addition, when abilities decline due to disease or head injury, knowing what is average for a person of a given age can be helpful in understanding the loss and marking recovery or further decline.

As a matter of context, clinicians usually administer other tests and conduct an interview to avoid interpreting test scores out of context.

Average intelligence is therefore, a middle range of abilities compared to other people of the same age who have taken the same test.

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Learn more about test and other statistics in

Applied Statistics for Counselors


See related books and resources at www.Suttong.com





Wednesday, October 25, 2017

How to Compare Test Scores

















When counselors and psychologists report test scores, they often report one of the scores found in the table below. When several tests are used, it is helpful to know how the scores compare from one test to another.

A good place to begin is to locate the average score-- that's the row where z = 0. Then look at the broad middle range between z = -1 and z = 1. About 68% of people score between z = -1 and z = 1.

Intelligence Tests use Standard Scores abbreviated as SS. These scores take the place of the old IQ score. An average IQ is 100 -- about 68% of people score between 85 and 115.


Here's a table from Appendix B of Applied Statistics: Concepts for Counselors



Each row contains the equivalent score on a different scoring system. For example, a z-score of 1 equals a T score of 60, and a standard score of 115. The score is at the 84th percentile.


z
T
Standard
Percentile
Rank
3
80
145
99.9
2.5
75
138
99.4
2
70
130
97.7
1.5
65
123
93.3
1
60
115
84.1
.5
55
108
69.2
0
50
100
50.0
-.5
45
93
30.8
-1
40
85
15.9
-1.5
35
78
6.7
-2
30
70
2.3
-2.5
25
63
0.6
-3
20
55
0.1




Table Notes

z-scores, M = 0, SD = 1
T-scores, M = 50, SD = 10
SS-Standard Scores, M = 100, SD = 15
PR- Percentile Rank


 Find more practical concepts in Applied Statistics: Concepts for Counselors

An inexpensive reference book for students and counselors















Learn more at the book's website  counselorstatistics

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Thursday, October 12, 2017

INTELLIGENCE TESTS - What Counselors & Psychologists Know





Intelligence tests (IQ tests) are in the news lately as people banter about terms from many decades ago. IQ tests are widely used because they measure the ability of people to solve various problems, predict academic achievement, and help with job placement in some settings. The tests also help neuropsychologists assess functioning in people with impairments due to head injuries and brain diseases.

During part of my childhood, I passed a facility where American IQ testing began. I saw people on swings and on the grounds of the Vineland Training school in Vineland NJ. It turns out that a little over 100 years ago, American psychologist, Henry Goddard, brought a test by French scientist, Alfred Binet, to the New Jersey Training School for Feeble-Minded Girls and Boys in Vineland, NJ. The test was modified and widely used in the U.S.

What tests are used today?

Today, a number of tests are available in the US and elsewhere. Popular American tests are the Wechsler Intelligence Scales and the Stanford-Binet Scale. The tests are regularly updated with new materials and tasks appropriate to people of different ages. Several other tests are also available such as the Kaufman Assessment Battery, Woodcock-Johnson Tests of Cognitive Ability, and the Differential Ability Scales.

A full scale test can last over an hour, so it is not surprising that a number of shorter tests are available. The shorter tests are considered "screening tests" because they include fewer subtests (or sets of tasks), to measure problem-solving skills. It is common to use a test of verbal ability such as vocabulary and a test of "nonverbal" ability such as tasks that require solving visually presented tasks.

Intelligence tests yield a variety of scores that recognize people have different abilities. This fits with common sense as we observe people with different abilities--strong verbal skills, incredible abilities to design complex structures, create various artistic works, and so forth. Still, many people want to know their IQ-- a short hand way of identifying an overall general ability. The overall score is controversial but remains in use.

In years past, the IQ (intelligence quotient) was measured as a ratio of chronological age to mental age. Mental age referred to a person's score on test tasks compared to others of the same age. As I posted previously, there are problems with age scores. Today, the scores on tests of intelligence compare people of similar ages to their age peers. For traditional reasons, the average IQ (or standard score) has an arithmetic average (M, mean) of 100 and a standard deviation (SD) of 15 points (read more about a few statistics).

It turns out that despite different test tasks and scales, people earn similar scores. An IQ score or standard score on one test is likely within a few points of the same score on a different test. As people age, the scores are more reliable-- that is stable. So, if an adult earns a score of 110 today, she would likely have a score within a few points of 110 in 2-years--unless something happened.

The stability of the scores make the tests useful when considering the effects of brain damage or disease. Of course, neuropsychologists use other tests as well (e.g., tests of memory, visual-spatial skills).


Read More


On AMAZON



What is average intelligence?

That can be a trick question unless you clarify what you mean by intelligence. On tests that report standard scores, the average score is 100. Using the common standard deviation of 15 points, about 68% of our age peers will score beetween 85 and 115. Close to 95% of people the same age will have scores in the range of 70 to 130. As you can see, only a small percentage of people score above 130 or below 70.

The test scores compare people to others of the same age. The skill levels develop rapidly in young children. Several months can make a difference in average scores. In adults, scores vary in how they change for people in large age brackets. Some abilities decline more rapidly than others. For example, young adults tend to be faster than older adults when solving tasks requiring eye-hand coordination.

What are some problems with IQ tests?

Test scores do not capture the range of abilities of people who are differently abled. For example, those with severe visual impairments cannot see visual test tasks. And those with severe hearing impairments may not respond well to spoken instructions or auditory tasks. Clearly, it would be wrong to assume something about a person's intelligence using tests that are not designed for people who have limited vision, hearing, or some other similar condition.

Some clinicians fail to document vision, hearing, or other limitations. For example, many people show up for testing and leave their eyewear at home. A child may forget his glasses or hearing aids.

People with temporary limitations cannot take tests as well as they could at other times. If you cannot use your dominant hand due to an injury, you will have difficulty on tests that require using your hands.

People taking medication can respond differently when taking medicine that either helps or interferes with attention and concentration. Of course, illegal drugs can also affect the brain processes needed to remember instructions and solve problems.

People who are not fluent in the language of the test may have a difficult time depending on their language skills.

So called "nonverbal tests" measure different abilities than tests that include language so mistakes can be made when making judgments about general intelligence or ability.

Clinicians make mistakes in recording information, scoring, or writing reports.

Tests are not perfect measuring instruments. Even when administered to people under the best of circumstances, there is measurement error. Measurement error is usually more variable for children than for adults. Measurement error refers to a variation in scores from one administration to another.

What about labels?

I suppose we will have a hard time escaping labels. The words used for people getting high scores or low scores have changed over the years--too many to cover in this post. Insulting words about a person's intelligence were terms used many decades ago. Today, clinicians and organizations like schools use a variety of terms focused on helping high scoring students learn in more challenging environments. And students who score very low on several tests, are elligible for services designed to help them maximize their potential. Insurance programs use cutoff scores and other criteria when awarding benefits to people with severely impaired abilities.

Who administers IQ tests?

A variety of professionals are qualified to administer, score, and interpret IQ tests. They are most commonly used by School Psychologists in schools and private practices. But other psychologists who specialize in neuropsychology also use IQ tests as part of their assessment. Many school counselors also have the necessary skills. In some cases, a psychological technician will administer the tests but the interpretation is left to the clinian holding an advanced degree along with the appropriate license or certification.

Read more


Applied statistics: Concepts for counselors. 

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You can also read more about the assessment of"thinking" in Creating Surveys.






Books by Geoffrey W. Sutton

www.suttong.com




Average Intelligence

  The concept of average intelligence is sometimes difficult to appreciate because the two words, average and intelligence, are sometimes no...