Organizing and classifying data into tables involves cleaning data, sorting values, and entering the number of classes. The general rule for the number of classes is 5-20 classes; Sturges' rule: k ≈ 1+log2(n). Class width h = (Xmax−Xmin)/k. Each class has a frequency (fi), relative frequency (pi=fi/n), cumulative frequency (Fi). Class center mi = (lower+upper)/2. If classes are not equal, frequency density fi/h is used.