When analyzing data, the selection of appropriate statistical methods requires careful consideration of the purpose of the analysis, the level of measurement, the number of groups, and the number of variables involved. The objectives of data analysis can generally be classified into three categories: (1) comparison, (2) determination of association, and (3) prediction. In other words, it is necessary to first determine whether the goal is to describe the distribution of a particular group, to examine the existence and strength of relationships between variables, to assess the effect of an intervention, or to predict a certain phenomenon.