NTA N-Test Alpha

The N-Test Alpha represents a reliable realization of Thurstone's N-factor. It enables the measurement of the ability to handle a system of symbols in an automatical way.

Application
The test is primarily conceived for personnel selection, career counseling, personnel selection, diagnosis and assessment. Additional areas of use are within clinical settings. It is also used for training purposes at universities and colleges.

Theoretical Background
The primary object of measurement is Numerical ability. The factor analytic school of intelligence research has identified this factor - N – as a primary intelligence factor. However, the name  Numerical ability is an unfortunate one as it leads to the wrong conclusion that it concerns numbers and arithmetic only. The domain is broader than that. It concerns the ability to apply the rules of a symbol system (any symbol system, not only the number symbol system) in an automated way on tasks, which were originally solved by means of logical thinking. Thus, it should be called Symbol system factor.

NTA measures not only the Symbol system factor but can also be used as a simple test for the assessment of Calculation capacity (defined as the ability to handle each of the basic arithmetic operations - addition, subtraction, multiplication and division – no matter if that is done automatically or not).

Testing
NTA consists of 20 groups of tasks. Within each group two stimulus numbers have in turn to be added to each other, subtracted from each other, multiplied with each other and finally divided with each other. E.g. 5+8, 5-8, 5x8 and 5/8. Thus, the total number of tasks is 80. No calculation can be passed over; the subject is required to give an answer.

Scoring
Each correct answer is scored as one point. In addition to the total score, the sum of correct answers is available separately for each of the four basic calculation operations. The print-out shows raw and standard scores.

Reliability
The reliability according to Cronbach’s Alpha (Cronbach, 1966) is 0.91 for different education levels.

Validity
The face validity with respect to the assessment variable Calculation Ability is undoubtedly high – the respondents think immediately of “calculations, arithmetic”. The assessment variable Symbol system factor, on the other hand, is probably nor quite as evident. The logical  validity is given by the operational definition of the measurement content. The construct validity has been proven through correlation with a test of Calculation Ability. Prognostic validity could be demonstrated for occupations demanding, amongst other prerequisites, to be able to apply the basic calculation operations in an automated way. Criteria used where “completed occupational education without complications” and “poor performance on the job”.

Norms
Samples of n=1587 Swedish adults as well as n=217 Austrian adults are available. Subsamples according to educational level and age are also presented.