4Assumptions in Parametric Tests
4.1 Introduction
“Statistics is a branch of mathematics dealing with the collection, analysis, interpretation, presentation, and organization of data” (Triola 2001). Another definition of statistics is the art and science of learning from the data. Statistical analyses can be divided into two categories: descriptive statistics and inferential statistics. Descriptive statistics comprises the methods for data representation by calculating descriptive figures, creating the summary graphs, or both. Descriptive statistics commonly uses figures/tables that include the frequencies, percentages, measures of central tendency, and measures of variation. Each of these descriptive figures uniquely summarizes the data (by various estimators) for better understanding the characteristics of data in hand. Also, the descriptive analysis gives useful information before starting the statistical inference, subject to the assumption that the sample is randomly drawn from the target population.
The results of descriptive analysis help the researchers and practitioners to have an overview and some reasonable idea about the population from which the random sample is drawn. The sample descriptions are then used to infer some information about population with some uncertainty by testing the stated research hypothesis and constructing the confidence interval for the respective parameters based on their estimates. The statistical procedures can thus be regarded as scientific ...