Characteristics of Psychological Testing

The diversity of psychological tests is staggering. Thousands of different psychological tests are available commercially in English-speaking countries, and doubtlessly hundreds of others are published in other part of the world. These test range from personality inventories to self-scored IQ tests, from scholastic examinations to perceptual tests. Yest despite this diversity several features are common to all psychological tests and taken together serve to define the term test.

A psychological test is a measurement instrument that has three defining characteristics:

• A psychological test is a sample of behavior.
• The sample is obtained under standardized conditions.
• There are established rules for scoring or obtaining quantitative (numeric) information from the behavior sample.

Behavior Sampling


Human sample of behavior is a complex phenomenon.We cant measure the human behavior at any cost, because it starts from birth and remains till death. Incidental behavior is not listed in sample of behavior. it based on specific human behavior.

Every psychological test requires the respondent to do something. The subject's behavior is used to measure some specific attribute(e.g Introversion) or to predict some specific outcome (e.g Success in a job training program).The use of behavior sample in psychological measurement has several implications. First a psychological test is not an exhaustive measurement of all possible behavior that could be used in measuring or defining a particular attribute. For example, You wished to develop a test to measure a person's writing ability. One strategy would be to collect and evaluate everything that person had ever written, from term papers to laundry lists. Such a procedure would be highly accurate, but impractical. A psychological test attempts to proximate this exhaustive procedure by collecting a systematic sample of behavior, In this case writing-test might include a series of short essays, sample letters, memos and the like.

The second implication of is the quality of a test is largely determined by the representativeness of this sample. For example One could construct a driving test in which each examinees was required to drive the circuit of a race track. This test would certainly sample some aspects of driving , but would omit others such as parking, following signals or negotiating in traffic. It would therefore not not represent a very good driving test.

Standardization


More over a test should be a standardized over representative sample of population to obtain norms.The result of some tests must be comparable within the population.
A psychological test is a sample of behavior collected under standardized conditions. The conditions under which a test is administered are certain to effect the behavior of the person or person taking the test. You would probably give different answers to questions on an intelligence test or a personality inventory administered in a quiet well-lit room than you would if the same test were administered at a baseball stadium during extra innings of a play-off game.A student is likely to do better on a test that is given in a regular classroom environment than he or she would if the same test were given in a hot, noisy auditorium. It is not possible to achieve the same degree of standardization with all psychological logical tests.

Individually administered tests are difficult to standardize because the examiner is an integral part of the test. The same test given to the same subject by two different examiners is certain to elicit a somewhat different set of behaviors. Through specific training a good deal of standardization in the essential features of testing can be achieved. Strict standard procedures for administering various psychological tests helps to minimize the effects of extraneous variables, such as the physical conditions of testing, the characteristics of the examiner or the subject's confusion regarding the demands of the test. A large diversity exist among different psychological test and thousands of different tests in the market.

Scoring Rules

The immediate aim of testing is to measure or to describe in a quantitative way some attribute or set of attributes of the person taking the test. The final defining characteristic of a psychological test is that there must be some set of rules or procedures for describing in quantitative or numeric terms the subject's behavior in response to the test. These rules must be sufficiently comprehensive and well defined that different exminers will assign scores that are at-least similar. For a classroom test these rules may be simple and well defined, the student earn a certain number of points for each item answered correctly and the total score is determined by adding up the points. For other types of tests the scoring rules may not be so simple or definite.

Most mass-produced standardized tests are characterized by objective scoring rules.In this case the term objective should be taken to indicate that two people each applying the same set of scoring rules to an individual's responses will always arrive at the same score for that individual. Thus two teachers who score the same multiple-choice test will always arrive at the same total score. On the other hand many psychological tests are characterized by subjective scoring rules.Subjective scoring rules typically rely on the judgment of the examiner.It is important to note that the term subjective does not necessarily imply inaccurate or unreliable methods of scoring responses to test, but simply that human judgment is an integral part of the scoring of a test. Most psychological tests are designed so that two examiners confronted with the same set of responses will give similar scores. A measure that does not meet this criterion cannot be considered a satisfactory example of a psychological test.

Norms

Scores on psychological tests rarely provide absolute ratio scale measure of psychological attributes.Thus it rarely makes sense to ask in an absolute sense how much intelligence, motivation, depth perception and so on a person has. Scores on psychological tests do however provide useful relative measures.It makes perfect sense to ask whether Scott is more intelligent, is more motivated or has better depth perception than Peter.Psychological tests provide a systematic method of answering such questions.

One of the most useful ways of describing a person's performance on a test is to compare his or her test score to the test scores of some other person or group of people.Many psychological tests base their scores on a comparison between each examinees and some standard population that has already taken the test.When a person's test score is interpreted by comparing that score to the scores of several other people, this is referred to as a norm-based interpretation.The score to which each individual is compared are referred to as norms which provide standards for interpreting test scores.A norm-based score indicates where an individual stands in comparison to the particular normative group that defines the set of standards.

Normative Group

Several different groups might be used in providing normative information for interpreting test scores.First No single population can be regarded as the normative group. Second a wide variety of norm-based interpretations could be made for a given raw score, depending on which normative group is chosen. These two points suggest that careful attention must be given to the definition and development of the particular norms against which a test score will be interpreted.

Types of Norms.

In some cases norms may be developed that are national in scope, as in the case of large achievement test batteries.

1. Percentile Ranks/Norms

The most common form of norms is percentile ranks, which represents the simplest method of presenting test data for comparative purpose. Percentile rank represents the percentage of the norm group that earned a raw score less than or equal to the score of that particular individual.It is possible to compare one's score to several different norm groups.

2. Age Norms

Many psychological characteristics change over time, vocabulary, mathematical ability and moral reasoning are examples.An age norm relates a level of test performance to the age of people who have taken the test.The principle involve in a developing age norms is fairly simple, they can developed for any characteristic that changes systematically with age-at least up to some age level.Second we need to obtain a representative sample at each of several ages and measure the particular age-related characteristics in each of these samples.While age norms tend to emphasize the average level at a given age, it is important to remember that there us considerable variability within the same age, which means that some children at one age will perform on this test similarly to children at other ages.

3. Grade Norms

Another type of norm commonly used in school setting is called a grade norm.Grade norms are very similar to age norms.These norms are most popular when reporting the achievement levels of school children.The interpretation of grade norms is similar to age norms.In areas such as emotional and social growth as well as in other achievement areas the child may not perform at the grade equivalent.