The Key Indicators of the Normality of Distribution

Abstract

Statistics plays an important role in describing the results of various research. The basic role of statistical reasoning is to enable generalizations valid for the entire population to be made on the basis of certain quantitative characteristics of the sample. Various statistical procedures are used for this purpose, among which those for which the normality of distribution is the null hypothesis are very common. This paper provides an insight into the statistical techniques most commonly used in pedagogical research, which serve as a guide for the researcher in confirming or rejecting the null hypothesis about the normality of the distribution of the population characteristics based on a simple random sample. These are commonly known descriptive methods that allow the researcher to statistically confirm the normality of the characteristics of the entire population. The first part of the paper describes the most commonly used visual methods: histogram, QQ graph, and scatter diagram, pointing out their advantages and disadvantages, but also the interrelation and a complementary role in drawing conclusions. Statistical tests are described as well: Chi-square, Shapiro-Wilk and Anderson-Darling tests, the application of which contributes to the discovery of the essence, which is not possible only by applying visual methods. The correctness of statistical inference is always conditioned by the adequate application of the selected methods and techniques. The aim of this paper is to present the application of statistical methods in determining the normality of the distribution of the features of empirical pedagogical research.

Keywords

• statistics
• analysis
• normal distribution
• visual methods
• normality tests