Unicorn: A Program for Transforming Data to Approximate Normality

Abstract

Unicorn, a BASIC computer program that automates the Box-Cox transformation, is described. Unicorn reads free field ASCII data files, is completely interactive, and is user friendly. Unicorn can handle files with or without missing data. Descriptive statistics and tests of normality are provided for each variable in untransformed format. Statistics include the first four moments of the distribution, the third and fourth L-moments, the Kolmogorov-Smirnov test, and D'Agostino et al.'s tests of normality. The user is then offered a choice of minimizing skewness or departures from normality overall. The optimal transformation is then found and descriptive statistics and tests of normality are provided for the transformed data. A new ASCII data file is written with transformed data. This new data file is then available for further analysis.