In the social sciences, there are essentially two major types of statistics tests parametric and non-parametric tests. The parametric tests are used when the variable have normal distributions and the subject are randomly selects from the population. This is usually tested by ascertaining the skewness and kurtosis. When these two values lie between -2 and +2 , the distributions are considered normally distributed and the thus amenable to parametric statistics testes like Pearson Product - moment Correlation, r or t-tests or Analyses of Variance. Normality are also statistics tested using the Kolmogorov-Smirnov tests or Sharpiro - Wilk tests. However, these two tests impose very stringent tests for normality.