Standard value

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The distribution of intelligence in a population and in an age group (around 30 to 35 year olds) is expressed by the intelligence quotient . The standard deviations are SD = 15

Normwert is a term from psychology and medicine . The norm value serves to classify the characteristics of an individual in relation to the totality of all individuals. Standard values ​​are obtained by a researcher examining a sufficiently large sample of the population to be examined using a measuring method and thereby making it possible to classify an individual characteristic expression. As a rule, a quasi-continuous distribution of the characteristic quality is assumed here. The original measured value is called the raw value .

After establishing the norm values, another researcher or examiner can examine a person using the same measurement method and then relate the individual to the population of the norm sample. Furthermore, the development of various characteristics of a person can be assessed by comparing them using the standard values. The norm sample should be large enough that it can represent a representative image of the population. It also makes sense to categorize the norm sample based on certain characteristics and to determine the norm value according to the characteristics. For example, the norm sample for an intelligence test can be divided into different age groups and according to gender. In addition, a further classification could be made based on the level of education.

Standard value scales

There are various standard value scales that can be converted directly into one another. The best known of these scales is the IQ scale . An IQ value of 100 corresponds exactly to the mean. Further scales are the z-scale, the T-value scale, the Stanine-value, the centil- (C-scale) and the standard value-scale (SW-scale). The percentile rank (PR) differs from these scales, indicating which percentage of the norm sample has an equally high or lower characteristic value. A PR of 50 means an average result, a PR of 10, on the other hand, that only 10% of the norm sample had an equal or lower result. As a rule, it is assumed that normal value scales are normally distributed .

Standard values ​​as threshold values

In medicine, the normal values ​​are often limit values from which it can be read off whether a value is possibly considered to be pathological or not. The standard values ​​are obtained in the same way as in psychology: a sufficiently large sample of the population to be described is examined. The values ​​that the lowest 2.5% (percentile rank 2.5 and lower) and the highest 2.5% (percentile rank 97.5 and higher) of the examined healthy persons are used as the norm value limits. However, a value outside the norm does not always have to be pathological. It can also only be particularly good or represent a standard variant . In paediatrics and adolescent medicine, the limits PR 10 and PR 90 are set for some areas in order to check whether the child is within a development corridor.

See also

literature

  • Markus Pospeschill: Empirical Methods in Psychology . tape 4010 . UTB, Munich 2013, ISBN 978-3-8252-4010-3 .
  • Jürgen Bortz , Nicola Döring: Research methods and evaluation: for human and social scientists . 4th, revised. Edition Springer, Berlin, Heidelberg 2006, ISBN 978-3-540-33305-0 .

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