MS Excek (the name is derived from the spreadsheet used by accountants to record financial information) is a computer program that presents a rectangular matrix of rows and columns to display data (see Figure 1). Each cell can contain numerical or textual data. Columns are defined by letters and rows by numbers. Cells are referenced as the intersection of those two criteria, A1 or D37, for example. In this figure, each row contains the information for one case, in this instance for one patient. Each column represents a variable (gender, date of ...