Norm scores help to compare attributes of individuals to a norm population and to determine if the scores lie within the normal range or if they are extreme. The conversion of individual scores into norm scores is usually based on the assumption that the values within the population are normally distributed. This means that many people have scores around the arithmetic mean and only few people have scores deviating extremly from the population mean. Normal distributions are characterized by their mean M and their standard deviation SD. The standard deviation is a measure for the variability within the distribution (i.e. its width). A norm score expresses the distance of an individual scored from the mean in terms of standard deviations.
There are a number of different norm scales. They all more or less yield the same information and can directly be transformed into each other. Probably the most well known scale is the IQ scale with a mean of 100 and a standard deviation of 15. A score of 100 means that the result is completely on average. 115 and more are usually perceived as above average, under 85 is substandard. The scores may as well be reported as z scores (M = 0, SD = 1), T scores (M = 50, SD = 10), Standard Values (SW score; a norm scale used in German speaking countries; M = 100, SD = 10) or Centil scores (M = 5, SD = 2), and even in quite a number of other scales.
Percent ranks, on the other hand, provide a different kind of information. They specify, which percentage of the norm population scores equal or worse. A percent rank of 50 means that 50% of the norm population score equal or worse. A person with percent rank 50 therefore shows an average result. Higher values indicate a better result, lower values a worse one.
The Norm Scale Calculator alleviates the conversion of the different scales. Either you can directly type scores into the text fields and the program does the transformation, or you can drag the slider to the desired score (User Guide). The Norm Scale Calculator is integrated into our different test analysis software products by default, e. g. the programs WPPSI III, WISC-IV, WIE, Hawik 4, DEMAT 1+ / 2+, DEMAT 3+ / 4, EBSK and RZD 2-6. Additionally, you can calculate the age of the person at the time of the testing.
You can find a more detailed overview of the programm function in the Online-Help.
In case, you do not need a visualization or the calculation of confidence intervals, the following small conversion utility might be of use for you. It converts different norm scales like IQ values, T values, standard values (e. g. IST-2000R), value points from Wechsler Intelligence Scales and percent ranks. Please fill in a value into a field and press return:
|Value Point (Wechsler)|
The Norm Scale Calculator may be used free of charge for privat or vocational activities (e.g. as psychologist, therapist ...). The software and any authorized copies that you make are the intellectual property of Psychometrica. You agree to hold Psychometrica harmless from any and all liabilities, losses, actions, damages, or claims (including all reasonable expenses, costs, and attorneys fees) arising out of using the software if they are not deliberately intended or caused by grossly negligent behavior of Psychometrica and its suppliers. We do not grant you the right to sublicense or distribute the software. You may not modify, adapt, translate or create derivative works based upon the software. You will not reverse engineer, decompile, disassemble or otherwise attempt to discover the source code of the software except to the extent you may be expressly permitted to reverse engineer or decompile under applicable law.
If you like the program, we would appreciate if you could set a link on a homepage, in a blog or a forum pointing to the download page of the Norm Scale Calculator (http://www.psychometrica.de/normwertrechner_en.html). For this, you can use the following piece of HTML code.
The version for Windows is an exe file, the jar is an platform independent executable. Please save the desired file on your computer an start it with a double click. If you wish to install the software, please use Webstart. Depending on the version of your Java platform, you might receive a warning message, because it is a piece of software from the internet. It is save to use it and it only stores its settings on your computer. If this troubles you, you might as well use the Online-Calculator though.
The Norm Scale Calculator needs an installed Java Runtime Environment (Version 6.0 or higher) on the computer. If Java is not yet installed, it can be obtained for free via http://java.com/.