Psychological Testing You are familiar with devices used to measure physical characteristics: the bathroom scale to measure your body weight, the ruler to measure length or distance. But what about psychological characteristics such as introversion/extroversion, aptitude, or intelligence? For those characteristics, too, there are special devices used to measure them, called psychological tests. In fact, these are real measuring instruments, and are sometimes actually referred to as instruments. To be of any value, psychological tests must have certain properties. In this paper I describe those characteristics and how we go about assessing them. After that, I review a selected sample of psychological tests.
Properties of a Good Psychological Test Three important properties of any good psychological test are validity, reliability, and (where appropriate) standardization. Below I define each of these properties and describe ways in which those properties are established.
Validity A psychological test is said to be valid if it measures what it is intended to measure. An intelligence test, for example, is valid to the extent that it does measure intelligence and not simply some other variable, such as knowledge. A number of ways to assess the validity of a test have been developed; here I will describe a few of them.
Concurrent Validity -- results of the test agree with those of another test of accepted validity as a measure of that characteristic. A newly developed test of intelligence would be considered to have concurrent validity if it gave the same I.Q. values (within measurement error) as an established intelligence test. Predictive Validity -- predictions based on the results agree with what one would expect if the test is a valid measure of the characteristic. A newly developed test of intelligence would be considered to have predictive validity if those who score high on the test tend to do very well in academic settings or other areas thought to require high intelligence, while those who score low on the test do poorly in those areas. Face Validity -- examination of the test reveals that the test appears to measure what it is intended to measure. For example, a test of mathematical aptitude contains mathematical and logical problems to solve. Face validity is a relatively poor index of the validity of the test as gaged by other methods -- a test may have low face validity and yet prove to have good predictive validity, for example.
Reliability
A psychological test is reliable to the extent that it produces similar results when the individual is repeatedly tested under the same conditions. There are two main methods used to assess reliability, described below.
Test-Retest Reliability -- the same individuals ar given the test twice, separated by some interval of time. The Pearson r correlation is then computed on the pairs of scores across individuals. A test is said to have high test-retest reliability if the correlation is 0.95 or better (where 1.0 equals perfect reliability). Test-retest reliability is useful for tests of characteristics that change only slowly over time, such as intelligence. If the characteristic changes between administrations of the test, then the test reliability will appear to be low, when it fact the test may be reliably tracking real changes in the characteristic. Another potential problem with this method is that individuals may remember their answers on the first administration of the test and simply repeat those answers on the second. If they do, then the test will appear to be more reliable than it really is. To avoid this problem, testmakers sometimes produce an alternate form of the test, which is supposed to be equivalent to the original but with somewhat different items. However, this introduces another problem, that of assuring that the two versions are indeed equivalent.
Split-Half Reliability -- individuals take the test and then the items are divided into two equivalent halves, which are then separately scored. The pairs of scores for each test are then correlated as in the test-retest method. The split-half method has the advantage that no time elapses between "administrations," so the characteristic being measured cannot change. However, the method has the same disadvantage as the use of alternate forms with the split-half method: the split halves may not be exactly equivalent and, if not, then the true reliability of the test will be underestimated.
Standardization In tests of physical characteristics such as weight, it is possible to establish the accuracy of the measurement by comparing measurements against a set of known standards. For example, a scale could be checked against standard weights of 50 grams, 100 grams, 500 grams, and so on. If inaccuracies were found, the scale would be calibrated to remove them. Standard samples for many variables are available from the National Bureau of Standards. For psychological characteristics, there are no standard samples that one can purchase and use to evaluate the accuracy of the test. (For example, you cannot rent a person known to have an I.Q. of exactly 100.) Thus, to standardize psychological tests, a different method is needed. What is actually done is to administer the test to a large sample of individuals from the population for which the test is intended, and then compute certain group statistics, usually the mean and standard deviation. These provide the average value across individuals and the amount of
variability, and are used to determine a formula for converting raw scores to standard scores. For example, different I.Q. tests are standardized so that the average I.Q. on the test is 100.
Some Examples of Psychological Tests Psychological tests abound; here I provide only a few major categories and examples.
Intelligence Tests -- these measure aspects of intelligence that contribute to good academic performance. I'll provide more information on these later. Personality Tests -- these measure personality characteristics. Different tests measure different characteristics, according to the theory of personality on which they were based. Examples include: o Minnesota Multiphasic Personality Inventory -- measures personality traits on several scales based on true-false answers to 500 statements. Scale values are plotted on a set of parallel scales and the dots are connected by lines to form a "profile" used in diagnosis and assessment. Objectively scored. o Thematic Apperception Test (TAT) -- individual is shown a series of 8" X 10" cards, each depicting a scene of some sort, and is asked to tell a story based on that scene. Designed to allow the person to "project" something about himself or herself into the answers (a type of projective test). Not objectively scored. o Rorshack Inkblot Test -- individual is shown a series of left-right symmetrical inkblots and is asked to describe what he or she sees there. Another projective test. Aptitude Tests -- designed to indicate an individual's aptitude or talent in some area. It works by assessing the degree to which the individual already has the requisite knowledge and skills required. The SAT that high-school students take for admission to college assesses your aptitude for college-level work. In fact, it was once called the "Scholastic Aptitude Test," but has been renamed for political reasons. Achievement Tests -- these measure what an individual knows or can do. A familiar example to Indiana students is the ISTEP test, designed to assess what Indiana primary and secondary school students have learned. Interest Inventory -- I like to mention this one because I took it myself as an undergraduate and found it helpful when I was trying to decide on a career. The tests asks you to indicate, for each of a large number of activities, what you are interested or not interested in doing. Your results are compared to the pattern marked by successful individuals in each of a variety of occupational fields. If your responses match up well with those of, say, a successful architect, then you would probably enjoy the sort of work an architect does. This does not tell you, however, whether you have any aptitude for the work! (For that you need to take other tests.)
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Unit 3.
How Psychologists Do Research (cont'd)
Psychological Tests: Superficially, psychological tests may seem a lot like surveys. There are some very important differences, however. Psychological tests are generally used to gather information about an INDIVIDUAL, whereas surveys are usually used to gather information about a group. Furthermore, psychological tests can be used to rate an individual's characteristics relative to the rest of the population, whereas surveys are designed to determine characteristics of the population itself. Good psychological tests must have several characteristics: 1.
Psychological tests must be STANDARDIZED. This means that uniform procedures for administering and scoring the test have been established, so that everyone takes the test under pretty much the same conditions.
2.
The test must have established NORMS. Norms are the scores that were obtained with an initial group of people took the test. Once the test has been normed, an average score and a typical range of scores can be determined. This makes it possible to know whether a particular score is unusually high, unusually low, or in the average range. Once the norms for a test have been established, the scores of everyone who subsequently takes the test are compared to the norms.
3.
The test must be RELIABLE. A reliable test is one that gives stable and consistent results. If a test said that you were an introvert the first time you took it, and the same test said that you were an extrovert when you took it again an hour later, that test would be an unreliable test. There are two common ways to measure the reliability of a test: Test-Retest Reliability - With this method, the same test is given twice to the same group of people. If the test is reliable, most people should obtain approximately the same score both times. If this is NOT the case, the test is said to be unreliable. Alternate-Forms Reliability - It is often not practical to give people the same test twice. (For example, people who have just taken an IQ test might look up the answers to items they did not know.) Under those circumstances another way to determine reliability is to administer two different forms of the same test. As with test-retest reliability, if the test is reliable,
people should make approximately the same score on both forms of the test. 4.
The test must be VALID. A valid test is one that actually measures what it says it measures. (For example, a valid test of knowledge of this chapter on research methods should have questions pertaining to this chapter, and should not include questions pertaining to the chapter on memory). There are several ways of measuring the validity of a psychological test. Only two of them will be discussed here: CONTENT (or FACE) VALIDITY - is determined by reviewing all of the items on a psychological tests and evaluating whether they appear to be appropriate for measuring the thing the test claims to be measuring. For example, if you are reviewing a vocabulary test and you find out that it contains mainly math problems, you should question the content validity of the test. CRITERION VALIDITY - is determined by comparing scores on the test to some other measure of the thing the test is claiming to measure. For example, if I developed a test that I claimed could accurately predict a student's grade in Psychology 1501, I could meaure its criterion validity by having a group of students take the test, then take Psychology 1501. I would then compare their scores on my prediction test with there end-of-the-term grades in the course. If my test has acceptable criterion validity, students who did well on the predictor test should also do well in the course. Course grades, then, function as the criteria to which scores on the predictor test will be compared.
http://facstaff.gpc.edu/~bbrown/psyc1501/methods/tests.htm
Characteristics of A Good Test 1- Validity: A test is considered as valid when it measures what it is supposed to measure. 2- Reliability : A test is considered reliable if it is taken again by the same students under the same circumstances and the score average is almost the constant , taking into consideration that the time between the test and the retest is of reasonable length. 3- Objectivity: Objectivity means that if the test is marked by different people, the score will be the same . In other words, marking process should not be affected by the marking person's personality. 4- Comprehensiveness: A good test should include items from different areas of material assigned for the test. e.g ( dialogue - composition - comprehension - grammar - vocabulary - orthography - dictation -
handwriting ) 5- Simplicity: Simplicity means that the test should be written in a clear , correct and simple language , it is important to keep the method of testing as simple as possible while still testing the skill you intend to test . ( Avoid ambiguous questions and ambiguous instructions ) . 6- Scorability : Scorability means that each item in the test has its own mark related to the distribution of marks given by ( The Ministry of Education http://wiki.answers.com/Q/What_are_the_characteristics_of_a_good_test
What are the Characteristics of good test in commerce? Nupur
A good test in commerce should have the following characteristics: (i) Validity: The test should be valid. It should fulfill the objectives for which it is meant. If our aim is to measure the ability V understand and application of commercial facts then language difficulty and speed should not come in way. Thus it should be free fron1 defects that are likely to affect the valid results. (ii) Reliability. Its test is considered to be reliable if it gives same results every times when it is used for testing the individual abilities under same conditions. An objective test is bound to be reliable. The reliability of a test is -affected by the following factors, to be reliable it should be free from: (a) The whims of an examiner. (c) The language of the questions-lack of clearness or any ambiguities in statements. (d) Lack of clear-cut instructions for marking (e) Inefficient methods of scoring. A reliable test is not influenced by subjective conditions, it is objective. (iii) Comprehensiveness. Any good test should be comprehensive i.e. it should assess knowledge, skills, abilities, attitudes etc. as adequately as possible. No aspect of the curriculum should be ignored while making evaluatation.
(iv) Administrable: It should be easy to administer, economical in time and money, easy to score and interpret. The directions of the test should be clear-cut. There should be answer-keys for scoring. (v) Capable of Maintaining the Interest of the Students. Any good test should be able to capture the interest of the students and maintain it. Thus it should be interesting for the students. A good test is motivating for the students and stimulates their best efforts. It should be neither too easy nor too difficult. It should never be used as a means of punishment. (vi) Diagnosticity. A good test is diagnostic. The aim of diagnostic is to analyse the difficulties of a students in a particular phase of work. The aim is to reveal reliable information concerning his weakness in order to overcome them by concentrated action and for remedial teaching In this way it would help the teacher to guide them properly and adopt remedial measures to eliminate their weak points. (vii) Utility. A good test is useful in various ways. For example a test result may be used for improvement of teaching, may be useful to measure some desired quality/ability in the student, useful in finding out deficiencies in pupils so that remedial measures be taken up for their removal etc. http://www.preservearticles.com/2012032829145/what-are-the-characteristics-of-good-test-incommerce.html
