Differential Aptitude Test (DAT)

The Differential Aptitude Test (DAT) is a widely-used psychometric assessment designed to measure an individual’s aptitude across a range of cognitive abilities and skills. Developed by the Psychological Corporation in the 1940s.

Introduction of Differential Aptitude Test (DAT)

‘An aptitude is a combination of characteristics indicative of an individual’s capacity to acquire with training some specific knowledge or skill, our set of organised responses, such as the ability to speak a language, to become a musician, to do mechanical work etc.’

There is no assumption that aptitudes are hereditary but rather are a result of the interaction between hereditary and environment.

Aptitudes are extremely broad. It embraces any characteristics which predispose to learning, including intelligence, achievement, personality, interest and special skills.

History

Intelligence tests were originally designed to sample a wide variety of functions in order to estimate the individual’s general intellectual level; it soon became apparent that such tests were quite limited in their coverage. And not all important functions were represented.

Even prior to World War 1, psychologists had begun to recognise the need for tests of special aptitudes to supplement the global intelligence tests. These special aptitude tests were developed particularly for use in vocational counselling and in the selection and classification of industrial and military personnel




Multiple aptitude testing batteries

The multiple aptitude batteries are designed to provide a measure of the individuals standing in each of a number of traits.

A separate score is obtained for such traits as verbal comprehension, numerical aptitude, arithmetic reasoning, perceptual speed etc.

Such batteries thus provide a suitable instrument for making the kind of intra-individual analysis or differential diagnosis that test users had been trying for many years to obtain.

Examples: One of the first multiple aptitude test battery was developed by Thurston, ‘Primary Mental Abilities Test’, GATB, ASVAB etc.

Description of  Differential Aptitude Test (DAT)

The original forms (A and B) of the DAT were developed in 1947 to provide an integrated, scientific, and well-standardized procedure for measuring the abilities of boys and girls in Grades 8 through 12 for the purpose of educational and vocational guidance. While the tests were constructed primarily for uses in junior and senior high schools, they have been also in the educational and vocational counselling of young adults out of school and in the selection of employees.

The DAT was revised and standardized in 1962 (Forms L and M) and again in 1972 (Forms S and T).

1962 revision- directed primarily at making the tests easier to administer and score through various changes in format and test length and by the elimination of ‘formula scoring’

1972 revision- Retained the earlier changes and in addition substantially updated five of the eight tests.

Now in its 5^th edition, (1992) the test has been periodically revised and stands as one of the most popular multiple aptitude test batteries of all time (Binnett, Seashore and Wesman, 1982, 1982)




Authors:

• George K. Bennett
• Harold G. Seashore
• Alexander G. Wesman

Year:

1. 1947 original test with 3 domains
2. 1962 revised to make the test easier for administration
3. 1972 revised 5 new domains added

Scoring: Hand Scoring and Machine scoring

Time:– 3 to 3 hours 30 minutes for the whole battery.

Reliability:

Split-half reliability, the coefficients were corrected by the spearman brown formula. (O.87 to 0.94) for boys. And (0.80 to 0.94) for girls.

Clerical speed and accuracy are, by design highly speeded. For this test only, the alternate form of reliability coefficients was computed. The values were: 0.79 to 0.89 for boys and 0.90 to 0.93 for girls.

Validity:

It was designed for practical application in counselling, placement and selection procedures. The test as measured on the basis of coefficient between DAT and grades to show satisfactory predictive validity.

Norms:

Over 100 school systems from all major geographic areas contributed to the normative sampling. The total no. of students included in the present form is over 47,000.

The States that contributed to the normative study of DAT were

Arizona, California, Colorado, Florida, Georgia, Iowa, Kansas, Kentucky, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Texas, Virginia, and Washington.

All the scores have been converted to 23 designated percentile values. The use of the finer percentile values have been purposely avoided since such units would give an appearance of exaggerated precision to the percentile ranking and to differences between rankings.

Percentiles and Stanine scores on each of the 8 tests.

Separate norms for girls and boys

Separate norms according to the grades are available too.

 Principles governing the test construction

• Each test should be an independent test
• The tests should measure power
• The test battery should yield a profile
• The norms should be adequate
• The test material should be practical

Verbal Reasoning

50 items.  Maximum possible raw score = 50. It is a measure of the ability to understand concepts framed into words. It is aimed at the evaluation of the student’s ability to abstract or generalize and to think constructively, rather than at simple fluency or vocabulary recognition.

The examinee must choose from among 5 pairs of words, the one pair that best completes the analogy.

The words used in these items may come from history, geography, literature, science, or any other content area. The item thus samples the students’ knowledge and his ability to abstract and generalize relationships adherent in that knowledge.

The Verbal reasoning test may be expected to predict with reasonable accuracy success in fields where complex verbal relationships and concepts are important

 Numerical Ability

40 items, Maximum possible raw score= 40

It designed to test understanding in numerical relationships and facility of handling numerical concepts. The problems are framed in the item type usually called ‘arithmetic computation’ rather than in what is usually called arithmetic reasoning’ This was prompted by the desire to avoid the language elements of the usual arithmetic reasoning problem, in which reading ability may play a significant role. The computation form has the advantage of not being thus contaminated as a measure of numerical ability.

Abstract reasoning

50 items, Maximum possible raw score=50

The abstract reasoning test is intended as a non-verbal measure of the students reasoning ability. The series presented in each problem requires the perception of an operating principle in the changing diagrams.

It involves the ability to perceive relationships in abstract figure patterns- generalization and education of principles from non-language designs.

Clerical speed and accuracy

100 items, Maximum possible raw score=100

The clerical speed and accuracy test are intended to measure the speed of response in a simple perceptual task. The student must first select the combination which is marked in the test booklet, then bear it in mind while seeking the same combination in a group of similar combinations on a separate answer sheet, and, having found the identical combination, fill in its answer space.

The clerical speed and accuracy test are designed to measure the students’ speed and accuracy with a simple number and letter combinations. It is the one test where the entire series places a heavy premium speed.  




                                          Mechanical reasoning

70 items, Maximum possible raw score=70

Each item consists of the pictorially presented mechanical situation together with a simply worded question. Care was taken to present items in terms of simple, frequently encountered mechanisms that do not resemble textbook illustrations or require specific knowledge.

The test is useful in those curricula and occupations where an appreciation of the principles of common physical forces is required

 Space relations

60 items, Maximum possible raw score=60

The ability to visualize a constructed object from a picture of a pattern has been used frequently in tests of structural visualization. Similarly, the ability to imagine how an object would appear if rotated in various ways has been used effectively in the measurement of space perception.

A feature inherent in these items is that they require mental manipulation of objects in three-dimensional space.

Spelling and Language usage

100 items for spellings and 60 items for language usage

Maximum possible raw score for both is 100 and 60 respectively.

All words on the first 2 editions of the test were selected from the lists in Gates’ Spelling Difficulties in 3876 Words (1937).

Example: “Spear” as a wrong spelling of “Spare”.

The language usage test intended to measure the student’s ability to detect errors in grammar, punctuation, and capitalization.

The two tests, spelling and Language usage are more nearly achievement tests than any of the others. The chief reason for their inclusion among the Differential Aptitude Tests is that they represent basic skills which are necessary for so many academic and vocational pursuits.




Indian Adaptation of DAT

The DAT has undergone several revisions and re-standardization to suit the Indian population. The Indian adaptation of the DAT was formulated by J. M. Ojha.

It includes 3 subtests from DAT:

1. Clerical speed and accuracy
2. Language usage – spellings
3. Language usage – Grammar.

Necessary Precautions

• The booklet should not be shown to the subject prior test administration
• Any kind of marking on the booklet is strictly prohibited
• The time limit should be strictly followed
• Instructions given by the experimenter must be clear to the subject.
• The experimenter should be a trained professional
• The career profiling should be done after the test administration with the help of the guidelines given in the Manual.
• Career counselling session or an orientation and feedback session should be carried out before and after the testing.
• Noise and other such distracting stimuli should be well controlled
• Under no circumstance should the score be interpreted as final indisputable evidence of an individual’s characteristics. The results provide only one small part of the information needed to help an individual make informed and realistic decisions and cannot be judged in isolation from other aspects of a person’s character including, job and other experiences, interests, goals, personality, values, family and environmental influences.

Applications

These tests can be used to help an individual

1. Choose among educational and career options based on strengths and weakness
2. Help an individual understand why they do well or poorly in certain subjects.
3. Can suggest new career options not previously considered.
4. Change or raise educational and career aspirations
5. Counselling individuals
6. The career profile of DAT can be used as a tool in career guidance.

Critical Evaluation 1

Remember aptitude tests do not measure many other qualities that are vital in successful careers such as, Determination to succeed, Enthusiasm and confidence, Energy to work long hours to achieve objectives, Determination to identify and find solutions to problems, Integrity, loyalty, and honesty, Commercial and entrepreneurial instinct, Initiative, creativity, and inventiveness, Ability to persuade and motivate others, Team spirit, Leadership, Ability to help others succeed, Empathy, Forward planning, Refusal to accept defeat, Sense of humour, Intrapersonal skills, Interpersonal skill, Having fun, Being socially responsibility, Having the skill to make friends, Independence, Impulse control, Stress tolerance, Being realistic, Optimism, Self-regard, Flexibility and adaptability, Being grateful etc.

   Critical Evaluation 2

• These tests have been standardised on different populations at different times for different purposes. Hence, if you say a student is ‘Average’, for one area, it surely doesn’t mean the same for the other four areas! Hence, the standardization sample should have been a constant sample.
• The operational definitions given by the authors are not available in the Manual.
• There is no clear cut distinction as to who developed which test between the 3 authors.
• The time required to administer this test battery is 3 to 3 and half hours which is too much for a child of 8^th to 12^th grade, as his attention span is very less than that.
• In the mechanical reasoning test, there is too much to read than actually understand and work out the problem and find the answer. The pictures too are not clear
• Though the Indian adaptation is available, there are only 3 tests available in the Indian adaptation, and not the full test battery.
• The clerical speed and accuracy test have too many problems to solve, which seem monotonous for the test taker.
• The difficulty level in the Numerical ability test is quite high. One cannot solve the questions without the help of rough work.