New: Continuous Norming with R (cNORM)
R package for generating continuous test norms in psychometrics and biometrics and for analyzing the model fit

## User Guide for the Norm Scale Calculator

Norms are useful to compare individual scores in a standardized test with the results of a representative population. The transformation of individual results into a normal score is usually based on the assumption of a normal distribution of personal traits or abilities within the reference group (see red line in the charts of the calculator). This means that many people have scores around the arithmetic mean and only few people have scores deviating extremly from the population mean.

A bunch of different scales exist which all aim at expressing the relative extremity of the scores. The Norm Scale Calculator simplifies the conversion between these different scales. You simply have to move the slider with the mouse or to enter the scores in the appropriate text field and press RETURN. The software tool automatically calculates all other scores.

#### Charts

The blue range within the charts highlights the normal range, indicating an avarage result. The dashed lines indicate the relative position of an individual compared to the reference population. There are two different distributions:

1. density: The density function of the normal distribution is shown.
2. cumulative: The cumulative density funtion is displayed. The y-axis shows the percentiles corresponding to the respective norm scores.

#### Age Calculation

In order to choose the correct normal score in psychological tests, it is necessary to calculate the exact age. Unfortunately, many errors occur at this stage of the analysis of the test results, potentially leading to drastic misinterpretations. Therefoe, with version 1.8 an age calculation module was introduced in the norm scale calculator. Please click on the calendar icon in the toolbar to start the age calculation.

#### Preferences

There are different conventions about which range is perceived as normal. The program has two different settings that influence the blue range marker and the verbal interpretation below the charts. You can access these settings via the "Tools" button:

1. "European Convention": The range between z-score -1 and +1 is set as the normal range. This equals 68% of the population.
2. "American convention": The normal range lies between percentile 25 and 75. The normal range therefore covers 50% of the population.

#### Norm Scales

The following norm scales are available:

 Mean Standard Deviation z-Score 0 1 T-Score 50 10 IQ-Score 100 15 SW-Score(= "Standard Value", a scale used in German speaking countries) 100 10 WECHSLER Subscale 10 3